- Auto-ignition based synthesis of Y2O3 for photo- and thermo-luminescent applications
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We present a simple route for synthesis of Y2O3 for both photoluminescent (PL) and thermoluminescent (TL) applications. We show that by simply switching the fuel from ethylene di-amine tetracetic acid (EDTA) to its disodium derivative (Na2-EDTA), we obtain a better photoluminescent material. On the other hand, use of EDTA aids in formation of Y2O3 which is a better thermoluminescent material. In both cases pure cubic nano-Y2O3 is obtained. For both the material systems, structural characterization, photoluminescence, thermoluminescence, and absorbance spectra are reported and analyzed. Use of EDTA results in nano Y2O3 with crystallite size ~10 nm. Crystallinity improves, and crystallite size is larger (~30 nm) when Na2-EDTA is used. TL response of Y2O3 nanophosphors prepared by both fuels is examined using UV radiation. Samples prepared with EDTA show well resolved glow curve at 140 C, while samples prepared with Na2-EDTA shows a glow curve at 155 C. Effect of UV exposure time on TL characteristics is investigated. The TL kinetic parameters are also calculated using glow curve shape method. Results indicate that the TL behavior of both the samples follow a second order kinetic model.
- Hari Krishna,Nagabhushana,Nagabhushana,Chakradhar,Sivaramakrishna,Shivakumara,Thomas, Tiju
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- Synthesis and luminescence properties of Y2O3:Eu with flower-like microstructure
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Europium-doped yttrium hydroxide (Y(OH)3:Eu) with flower-like microstructure has been successfully prepared via a facile hydrothermal process, using potassium sodium tartrate (C4H4O6KNa) as a structure-directing reagent. Europium-doped yttrium oxide (Y 2O3:Eu) with similar morphology is prepared by calcining the as-prepared Y(OH)3:Eu at 700 °C for 4 h. Influencing factors such as the concentration of potassium sodium tartrate, the amount of sodium hydroxide, and the temperature used for hydrothermal synthesis are systematically investigated. Possible formation mechanism for the flower-like microstructure is proposed on the basis of time-dependent experiment. Y 2O3:Eu samples show a strong red emission corresponding to the 5D0-7F2 transition of Eu 3+ ions under excitation. Emission intensity varies between samples with different morphologies. The optimum Eu3+ doping concentration is also explored. This work sheds some light on the design and preparation of novel microstructures.
- Zhang, Xuemei,Wang, Jiao,Guo, Kai,Chen, Haohong,Yang, Xinxin,Zhao, Jingtai
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- Spin-phonon coupling in multiferroic Y2CoMnO6
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Spin-phonon coupling in rare-earth based manganites with double perovskite structure plays a crucial role in the magnetoelectric properties of these ferromagnetic materials. Particularly, on Y2CoMnO6(YCMO), it is assumed that spin-phonon coupling is related to the induced ferroelectric polarization. This confers to YCMO a multiferroic characteristic. In this work, we probed the spin-phonon coupling in YCMO by temperature-dependent Raman spectroscopy measurements in ceramic samples obtained by the nitrate decomposition method. Raman scattering revealed some anomalies that could be attributed to a weak spin-phonon coupling, an unconventional behavior for rare-earth based manganites with double perovskite structure, in which the coupling does not fit with the quadratic magnetization.
- Silva, Rosivaldo X.,Castro Júnior, Manoel C.,Yá?ez-Vilar, Susana,Andújar, Manuel Sánchez,Mira, Jorge,Se?arís-Rodríguez, María Antonia,Paschoal, Carlos William A.
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- Studies on terbium doped apatite phosphors prepared by precipitation under microwave conditions
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In this study we present our first attempts to obtain silicate apatite phosphors by precipitation with NaOH under microwave conditions. Y and La precursors fired at different temperatures (800 °C÷1400 °C) led to phosphors with hexagonal apatite structure
- Muresan,Perhaita,Prodan,Borodi
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- Preparation and photoluminescence properties of SrY2O4:Yb3+, Er3+ powders
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Yb3+/Er3+ co-doped SrY2O4 powders are prepared by developing a nitric-decomposition method. Under 980 nm laser excitation, the green and red up-conversion emissions are observed at around 549 and 661 nm, which a
- Yang, Jikai,Xiao, Siguo,Ding, Jianwen,Yang, Xiaoliang,Wang, Xiangfu
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- The energy transfer phenomena and colour tunability in Y2O 2S:Eu3+/Dy3+ micro-fibers for white emission in solid state lighting applications
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This paper reports on the structural, optical and photometric characterization of an Eu3+/Dy3+ doped yttrium oxysulfide phosphor (Y2O2S:Eu3+/Dy3+) for near white emission in solid state lighting. A series of Y2O2S phosphors doped with Eu3+/Dy3+ were prepared by the hydrothermal method. The microstructures of the as-synthesized phosphors were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results reveal that the obtained powder phosphors have a single-phase hexagonal structure and also indicate that the incorporation of the dopants/co-dopants did not affect the crystal structure. The SEM images reveal the morphology of the prepared phosphors as an intense interpenetrating network of interconnected micro-fibers with a diameter of about 0.15 μm. The band gap of the phosphors was calculated from diffuse reflectance spectra using the Kubelka-Munk function. The Eu3+, Dy3+ doped and Eu 3+/Dy3+ co-doped phosphors illuminated with ultraviolet light showed characteristic red luminescence corresponding to the 5D0→7FJ transitions of Eu 3+ and characteristic blue and yellow luminescence corresponding to the 4F9/2→6H15/2 or 4F9/2→6H13/2 transitions of Dy3+. The luminescence spectra, the energy transfer efficiency and the decay curves of the phosphors indicated that there exists a strong energy transfer from Dy3+ to Eu3+ and this was demonstrated to be a resonant type via a dipole-quadrupole reaction. Furthermore, the critical distance of the Eu3+ and Dy3+ ions have also been calculated. By utilizing the principle of energy transfer it was also demonstrated that with an appropriate tuning of the activator content the Y 2O2S:Eu3+/Dy3+ phosphors can exhibit a great potential to act as single-emitting component phosphors for white light emission in solid state lighting technology.
- Som,Mitra,Kumar, Vijay,Kumar, Vinod,Terblans,Swart,Sharma
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- Soft-chemical synthesis and tunable luminescence of Tb3+, Tm3+/Dy3+-doped SrY2O4 phosphors for field emission displays
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Tb3+, Tm3+, and Dy3+-activated SrY 2O4 phosphors have been prepared via Pechini-type sol-gel method. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) and lifetimes, as well as cathodoluminescence (CL) spectra were used to characterize the samples. Under low-voltage electron beam excitation, the Tb 3+-doped samples show a green luminescence, with a better CIE coordinates and higher emission intensity than the commercial product ZnO: Zn. Blue and yellow emissions could be obtained by doping with Tm3+ and Dy3+, respectively. A color-tunable emission in SrY2O 4 phosphors can be realized by co-doping with Tm3+ and Dy3+. White cathodoluminescence (CL) has been realized in a single-phase SrY2O4 host by co-doping with Tm3+ and Dy3+ for the first time with CIE (0.315, 0.333). Furthermore, the cathodoluminescence (CL) properties of SrY2O4: Tb 3+/Tm3+/Dy3+ phosphors including the dependence of CL intensity on accelerating voltage and filament current, the decay behaviour of CL intensity under electron bombardment, and the stability of CIE chromaticity coordinate have been investigated in detail. The as-prepared phosphors might be promising for use in field-emission display (FED) devices.
- Zhang, Yang,Geng, Dongling,Shang, Mengmeng,Zhang, Xiao,Li, Xuejiao,Cheng, Ziyong,Lian, Hongzhou,Lin, Jun
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- The sonochemical and microwave-assisted synthesis of nanosized YAG particles
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Nanoparticles of YAG were prepared by sonochemistry and by microwave radiation. In both cases, the last stage of the preparation was annealing at a high temperature, which led to a highly aggregated product. To reduce the aggregation we have added κ-carrageenan (a sugar) to the reaction mixture. The effect of the sugar is presented and discussed herein. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Letichevsky, Yana,Sominski, Lena,Moreno, Jose Calderon,Gedanken, Aharon
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- Sol-gel synthesis and photoluminescence of K2NiF4-type structure phosphors CaxSr1-xGdyY1-yAlO 4:zEu3+ with hybrid precursors
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CaxSr1-xGdyY1-yAlO 4:zEu3+ (x = 0.2-1.0, y = 0-1.0, z = 0.01-0.07) was synthesized by a hybrid precursor assembly sol-gel technology. We got sol solutions by stoichiometric rare earth nitrate, Sr(NO3)2, Ca(NO3)2, Al(NO3)3, at the same time investigated the relationship between the sol formed and experiment variable including Ph, temperature, concentration, and so on. Through drying and calcining precursors, we got luminescent materials powder. The particle size of luminescent materials is about 40 nm characterized by XRD and having thick three-dimension grains as SEM shown. Not only co-doping Ca2+ and Sr2+ but also changing the ratio of Gd3+ and Y3+ cannot change the crystalline structure in CaxSr1-xGdyY1-yAlO 4, it also formed the crystalline structure as that of pure-phase CaGdAlO4. All these photoluminescence materials show good emission spectra and their luminescent intensity depend on the concentrating of Eu3+: in all these luminescent materials, there exist emission come from Eu3+ activator' transitions of 5D0-7FJ (J = 0-3) and their emission intensity increase as adding to the concentration of Eu3+.
- Wu, Junjie,Yan, Bing
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- Synthesis of nanocrystalline YFeO3 and its magnetic properties
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Single phase nanocrystalline YFeO3 has been synthesized by a simple solution method. The average particle diameter is 42.2 nm. The particles exhibit ferromagnetic behaviour in the temperature range 10-300 K with a coercivity of 23 kOe. The magn
- Maiti, Ramaprasad,Basu, Soumen,Chakravorty, Dipankar
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- Controllable preparation and fluorescence properties of Y3+ and Eu3+ co-doped mesoporous silica
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The controllable preparation and forming mechanism of rare-earth Y3+ and Eu3+ chemically co-doped fluorescent mesoporous silica were studied in detail. Their structures, morphologies, chemical compositions and emission properties were characterized and evaluated by small angle X-ray scattering, nitrogen adsorption/desorption measurements, high resolution transmission electron microscopy, inductive coupled plasma-atomic emission, X-ray photoelectron spectra and fluorescent spectroscopy. The results show that chemical composition of the resultant mesoporous materials were significantly affected by solution acidity condition, and can be effectively adjusted by varying the feed ratio of raw materials at a suitable solution acidity condition. These materials with a well-ordered two-dimensional hexagonal mesoporous structure and high specific surface area exhibit significantly broadened emission band from 526 to 682 nm and the fluorescent emission mechanism and influence of materials structure on optical properties were investigated.
- Zhang, Chao,Guang, Shanyi,Xu, Hongyao
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- Synthesis and characterization of nanosized powders of yttria-doped zirconia
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Zirconia-3 mol% yttria nanosized powders have been prepared following a chemical route. The aim of this work is to optimize the techniques of solid solution synthesis and processing to obtain nanophase sintered ceramics without using milling or other special procedures. To ascertain this, several characterization techniques have been used. The electrical resistivity of polycrystalline specimens was compared to that of a single crystal of similar chemical composition. The main results show that a monomodal distribution of pore sizes has been obtained. Total stabilization of the tetragonal phase and nanophase sintered ceramics with relative densities of 98% were prepared by sintering at temperatures lower than 1200°C. The main conclusion is that the optimization of the synthesis and processing techniques play a key role for improvement of chemical and physical properties of solid electrolytes prepared by chemical techniques. Elsevier Science B.V. All rights reserved.
- Tadokoro,Muccillo
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- Morphology formation mechanism and fluorescence properties of nano-phosphor YPO4:Sm3+ excited by near-ultraviolet light
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A series of YPO4:Sm3+ phosphors were prepared by the hydrothermal method. The composition, structure, morphology and luminescence properties of the samples were characterized and analyzed by means of X-ray diffractometer (XRD), scanning electron microscopy (SEM and EDS) and fluorescence spectrophotometer (FL). The morphology formation mechanism and fluorescence temperature characteristic of nano-phosphor YPO4:Sm3+ were mainly studied. The results show that the products are single tetragonal phosphor yttrium ore structure with nanosphere morphology. Morphology formation mechanism of YPO4:Sm3+ is nucleation - dissolution - recrystallization - crystal growth. The strongest excitation spectrum appears at 404 nm, which belongs to the 6H5/2 → 4F7/2 transition of Sm3+. The strongest emission spectrum appears at 603 nm, which belongs to the 4G5/2 → 6H7/2 transition of Sm3+. The chromaticity coordinates show that the phosphors are red. The optimum doping concentration of activator Sm3+ in YPO4 matrix is 2%. When the doping concentration of Sm3+ is higher than 2%, concentration quenching occurs. The mechanism of concentration quenching is electric dipole - electric dipole interaction. The critical distance for energy transfer between Sm3+ is 1.899 nm. Nano-phosphor YPO4:2% Sm3+ has good thermal stability, and its fluorescence lifetime is 217.99 μs. The activation energy of thermal quenching is 0.2566 eV.
- Wu, Jinxiu,Li, Mei,Jia, Huiling,Liu, Zhaogang,Jia, Hengjun,Wang, Zhongzhi
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- Soft chemical synthesis of NaYF4 nanopowders
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Hydrated NaYF4 powders dominated by the metastable high-temperature cubic phase were precipitated with a fivefold NaF excess from acid solutions of yttrium nitrate. Transformation into the stable hexagonal phase (a = 5.969(2), c = 3.503(1) ?) occurs under heating with an exotherm at ?400°C.
- Fedorov,Kuznetsov,Voronov,Yarotskaya,Arbenina
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- Color-tunable luminescence of Y4Si2N 2O7:Ce3+, Tb3+, Dy3+ Phosphors prepared by the soft-chemical ammonolysis method
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Ce3+-, Tb3+-, and Dy3+-activated Y 4Si2N2O7 phosphors have been prepared by the Pechini-type sol-gel method followed by ammonolysis of the precursors. The phase purity, morphology, crystallization condition, chemical composition, and thermal stability of the products have been studied carefully by X-ray diffraction (XRD), energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), fourier-transform infrared (FTIR), and thermogravimetry analysis (TGA) techniques. The photoluminescence (PL) and cathodoluminescence (CL) properties of Ce3+-, Tb3+-, and Dy3+-doped Y 4Si2N2O7 phosphors were also investigated. The electronic structure of Y4Si2N 2O7 has been investigated by density-functional theory methods. The calculations revealed that the nitrogen atom contributes more excited electrons than the O atom. The band gap has been calculated through the reflection spectrum of the Y4Si2N2O7 host. For Ce3+/Tb3+/Dy3+ singly doped Y 4Si2N2O7 products, the phosphors give the typical emissions of the activators. The energy transfers from Ce 3+ to Tb3+ and Dy3+ ions have been found and demonstrated through the PL spectra and luminescence decay times. The emission color of Y4Si2N2O7:Ce3+, Tb3+ and Y4Si2N2O 7:Ce3+, Dy3+ samples can be tuned by energy transfer processes. Additionally, the temperature-dependent PL properties and the degradation property of CL under continuous electron bombardment of the as-synthesized phosphors prove that the Y4Si2N 2O7 host has good stability. Therefore, the Y 4Si2N2O7:Ce3+, Tb 3+, Dy3+ phosphors could serve as a promising candidate for UV W-LEDs and FEDs. Copyright
- Geng, Dongling,Li, Kai,Lian, Hongzhou,Shang, Mengmeng,Zhang, Yang,Wu, Zhijian,Lin, Jun
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- Bi3+-Doped BaYF5:Yb,Er Upconversion Nanoparticles with Enhanced Luminescence and Application Case for X-ray Computed Tomography Imaging
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In this work, BaYF5:20%Yb3+/2%Er3+/x%Bi3+ (abbreviated as BaYF5:Yb,Er,Bix, where x = 0-3.0) upconversion nanoparticles (UCNPs) with various doping concentrations of Bi3+ were synthesized through a simple hydrothermal method. The influence of the doping amount of Bi3+ on the microstructures and upconversion luminescence (UCL) properties of the BaYF5:Yb,Er,Bix UCNPs was studied in detail. The doping concentration of Bi3+ has little influence on the microstructures of the UCNPs but significantly impacts their UCL intensities. Under excitation of a 980 nm near-IR laser, the observed UCL intensities for the BaYF5:Yb,Er,Bix UCNPs display first an increasing trend and then a decreasing trend with an increase in the ratio x, giving a maximum at x = 2.5. A possible energy-transfer process and simplified energy levels of the BaYF5:Yb,Er,Bix UCNPs were proposed. The potential of the BaYF5:Yb,Er,Bix UCNPs as contrast agents for computerized tomography (CT) imaging was successfully demonstrated. An obvious accumulation of BaYF5:Yb,Er,Bix in tumor sites was achieved because of high passive targeting by the enhanced permeability and retention effect and relatively low uptake by a reticuloendothelial system such as liver and spleen. This work paves a new route for the design of luminescence-enhanced UNCPs as promising bioimaging agents for cancer theranostics.
- Luo, Ran,Chen, Lei,Li, Qinyu,Zhou, Jie,Mei, Linqiang,Ning, Zhanglei,Zhao, Yan,Liu, Mengjiao,Lai, Xin,Bi, Jian,Yin, Wenyan,Gao, Daojiang
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- Photoluminescent properties of Eu3+, Tb3+ activated M3Ln(PO4)3 (M = Sr, Ca; Ln = Y, La, Gd) phosphors derived from hybrid precursors
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Ternary orthophosphates M3Ln(PO4)3 doped with Eu3+, Tb3+ were prepared via an in situ chemical co-precipitation technology, and the assembly process of hybrid precursors were as follows: using rare-earth coordination polymers with salicylic acid as precursors and composing with the polyvinyl alcohol (PVA) as dispersing media. Their microstructure and micromorphology have been analyzed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The emission spectra exhibited strong luminescence of 5D0 → 7F2 at 609 nm, indicating that the Eu3+ located in a noncentrosymmetric position in Eu-doped M3Ln (PO4)3 matrix. Besides this, the values of red to orange emission intensities for Eu3+ in Sr3Gd (PO4)3 strongly depend on the doping concentration.
- Xiao, Xiuzhen,Xu, Shuai,Yan, Bing
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- Radiative transition properties of Yb3+ in Er3+/Yb3+ co-doped NaYF4 phosphor
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Usually, it is difficult to quantitatively express the optical transition properties of Yb3+ in powdered samples owing to the difficulty in measuring the absolute absorption spectra. In this work, we developed an approach for confirming the abs
- Cao, Yongze,Chen, Baojiu,Li, Xiangping,Sui, Guozhu,Sun, Jiashi,Wang, Xin,Xu, Sai,Zhang, Jinsu,Zhang, Xiangqing,Zhang, Xizhen,Zhang, Yanqiu,Zhang, Yuhang
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- New rare earth langbeinite phosphosilicates KBaREEZrP2SiO12 (REE: La, Nd, Sm, Eu, Gd, Dy) for lanthanide comprising nuclear waste storage
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In contrast to the existing cubic langbeinite phosphates and sulphates, orthorhombic langbeinite phosphosilicates of the chemical formula KBaYMP2SiO12 (M: Zr, Sn), KBaREEZrP2SiO12 (REE: La, Nd, Sm, Eu, Gd, Dy) and the wasteform KBaY0.6La0.1Nd0.1Sm0.1Eu0.1ZrP2SiO12 have been synthesized by solution method. Powder X-ray diffraction analysis affirmed that the compounds were phase pure and crystallized in an orthorhombic structure with P212121 space group. Spectral analysis of the wasteform revealed the phase stability, thermal stability and chemical durability of the langbeinite structure. Chemical durability of the powder wasteform has been studied by a dynamic Soxhlet test. Elemental analysis of the leachates showed that the normalized mass losses of barium, zirconium and silicon were in the order of 10-3-10-2 g/m2, 10-5-10-4 g/m2 and 10-2-10-1 g/m2 respectively. Normalized mass losses of lanthanides, potassium and phosphorous were found to be below the instrumental detection limits.
- Kumar, Sathasivam Pratheep,Gopal, Buvaneswari
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- Thermal analysis of some polynuclear coordination compounds as precursors of iron garnets (M3Fe5O12, M=Y3+ or Er3+)
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The thermal behaviour of four coordination compounds (NH4) 6[Y3Fe5(C4O5H 4)6(C4O5H3) 6]?12H2O, (NH4)
- Patron, Luminita,Carp, Oana,Mindru,Marinescu,Hanss,Reller
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- Microstructure evolution in two-step-sintering process toward transparent Ce:(Y,Gd)3(Ga,Al)5O12 scintillation ceramics
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Scintillators are broadly utilized in high energy particle detection and medical imaging. Ce:(Y,Gd)3(Ga,Al)5O12 ceramics has recently demonstrated excellent scintillation properties and great commercialization potential. T
- Beitlerová, Alena,Chen, Haohong,Chen, Xiaopu,Feng, Yagang,Kou, Huamin,Ku?erková, Romana,Li, Jiang,Li, Xiaoying,Liu, Xin,Mihóková, Eva,Nikl, Martin,Xie, Tengfei
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- Energy migration in YBO3:Yb3+,Tb3+materials: Down- and upconversion luminescence studies
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Down- and upconversion luminescence phenomena from YBO3materials doped by Yb3+and Tb3+ions were observed and investigated. Materials described in the article were synthesized by a sol-gel method. Two series of products were prepared: with changed molar concentrations of Yb3+or Tb3+ions in the range from 1 to 30%. This way of doping was chosen to analyse the influence of ions concentrations on luminescence and to find samples with the most intense emission. Structural and morphological properties of the obtained materials were analysed on the basis of X-ray diffraction, infrared spectroscopy and by collecting images of samples from transmission electron microscope. The products were pure and well crystallized, showing monoclinic structure with C2/c space group. Spectroscopic properties of the YBO3:Yb3+,Tb3+materials were investigated by measurements of excitation spectra in the ultraviolet and near infrared range; emission spectra in the visible range; luminescence decays and dependencies of integral luminescence intensity on pumping laser energy. Based on careful studies of the obtained results, mechanisms responsible for the processes observed in these materials were proposed and explained.
- Grzyb, Tomasz,Kubasiewicz, Konrad,Szczeszak, Agata,Lis, Stefan
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- Highly uniform α-NaYF4:Yb/Er hollow microspheres and their application as drug carrier
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Highly uniform α-NaYF4:Yb/Er hollow microspheres have been successfully prepared via a simple two-step route. First, the core-shell structured MF@Y(OH)CO3:Yb/Er precursor was fabricated by a urea-based homogeneous precipitation method using colloidal melamine formaldehyde (MF) microspheres as template. Then the Y(OH)CO3:Yb/Er precursor was transformed into hollow NaYF4:Yb/Er (α and β mixed phase) by a subsequent solvothermal method, and MF microspheres were dissolved in the solvent simultaneously. The mixed phase of NaYF4:Yb/Er was transferred into pure α-NaYF4:Yb/Er by calcination. The as-prepared hollow microspheres were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrum (EDS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and upconversion (UC) luminescence spectroscopy. It is found that the template can be removed without additional calcination or etching process. α-NaYF4:Yb/Er hollow microspheres exhibit bright upconversion (UC) luminescence under 980 nm laser diode (LD) excitation. Furthermore, the hollow microspheres show sustained and pH-dependent doxorubicin hydrochloride (DOX) release properties; in particular, the emission intensity increases with the release amount of drug, making the release process able to be tracked or monitored by the change of the emission intensity, which demonstrates the high potential of this kind of hollow fluorescent material in drug delivery fields.
- Han, Yunhua,Gai, Shili,Ma, Ping'An,Wang, Liuzhen,Zhang, Milin,Huang, Shaohua,Yang, Piaoping
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- Matrix-inducing synthesis and luminescence of microcrystalline red phosphors YVO4:Pb2+,Eu3+ derived from the in situ coprecipitation of hybrid precursors
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Using rare-earth coordination polymers with o-hydroxylbenzoate as a precursor, composing with poly vinyl alcohol as a dispersing medium, a novel red-emitting material of YVO4:xPb2+, yEu3+ (x = 0, 1.0, 1.2, 1.5, 1.8, 2.0, and 5.0 mol %; y = 5 mol %) was synthesized by an in situ coprecipitation process. Its microstructure and micromorphology have been analyzed by x-ray powder diffraction and scanning electronic microscopy, which indicates that there exist some novel cobblestone-like microcrystalline particles. With Pb2+ as a sensitizer, these materials all exhibit strong red emission near 618 nm due to the 5D0 → 7F2 transition of Eu3+ ions. At x = 1.5, YVO4:Pb2+,Eu3+ shows the strongest emission intensity, which indicates an efficient energy transfer from Pb2+ to Eu3+. Pleiades Publishing, Inc., 2006.
- Su, Xue-Qing,Yan, Bing
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- Facile large-scale synthesis of monodisperse REF3 (RE = Y, Ce, Nd, Sm-Lu) nano/microcrystals and luminescence properties
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Highly monodisperse YF3:Ln3+ (Ln = Eu, Ce, Tb, Yb/Er, Yb/Ho, and Yb/Tm) nano/microcrystals with controllable size and morphology have been synthesized by an innovative low-temperature (≤0 °C) precipitation route free of any surfactant. Interestingly, the monodispersity and morphology are independent of the pH value and reactant concentration at a low temperature even when the reactant concentrations are close to saturation. This allows for a high yield production at 150 g L-1 of reaction system. A detailed investigation of the growth process reveals that a low temperature can ensure a more definite separation of nucleation and growth. Simultaneously, the low temperature-induced diffusion-controlled growth model gives rise to a size focusing effect, which further insures the monodispersity of the final products. Furthermore, our synthetic strategy can be extended to other lanthanide fluorides (REF3, RE (rare earth) = Ce, Nd, Sm-Lu), and the obtained YF3:Ln3+ samples exhibit strong down/upconversion emissions. Such a facile synthetic strategy fits well with the green concept in current synthetic innovations for nanocrystals and may provide some guidance in the kinetically controlled synthesis of inorganic nanocrystals. the Partner Organisations 2014.
- Shao, Baiqi,Zhao, Qi,Jia, Yongchao,Lv, Wenzhen,Jiao, Mengmeng,Lue, Wei,You, Hongpeng
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- Facile hydrothermal synthesis and luminescent properties of Eu-doped CaF2-YF3 alkaline-earth ternary fluoride microspheres
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Large-scale CaF2-YF3 alkaline-earth ternary fluoride microspheres with diameters of about 2.5 μm were prepared by a facile hydrothermal method in the presence of disodium ethylenediamine tetraacetate (Na2H2L). The influences of several experimental parameters, such as reaction time, amount of Na2H2L, pH values, and fluoride source on the final products were investigated. The formation mechanism of the as-obtained microspheres was proposed on the basis of all these studies. It is also found that the addition amount of the Y 3+ ions had an effect on the morphology of CaF2-YF 3. The luminescence spectrum of Eu3+-doped CaF 2-YF3 microspheres showed the strong characteristic dominant emission of the Eu3+ ions at 590 nm, indicating that the Eu3+ ions occupy a site of inversion symmetry in the CaF 2-YF3 matrix.
- Zhang, Yang,Zhao, Qi,Shao, Baiqi,Lue, Wei,Dong, Xiangting,You, Hongpeng
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- Rare-Earth Germanate Visible, Near-Infrared, and Up-Conversion Emitters
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The hydrothermal synthesis and structural characterization of new trivalent rare-earth germanates, Na4[(Y1–aLna)2Ge4O13] (Ln = Eu, Tb, or Yb and Er; a = 0.05, 0.1) and Na4[(Yb0.9Er0.1)2Ge4O13] are reported. The structure of these solids was solved by single-crystal X-ray diffraction (150 K). The materials crystallize in the orthorhombic non-centrosymmetric Pna21 space group, and exhibit a framework comprising unprecedented anionic tetrameric [Ge4O13]10– units, tetrameric units of {GeO4} tetrahedra, and isolated dimeric units encompassing two distinct distorted {REO6} octahedra. These rare-earth germanates feature interesting photoluminescence properties in the visible and near-infrared spectral regions. Eu3+ photoluminescence confirms the presence of two distinct rare-earth sites. Energy transfer between the latter sites is shown for the Yb3+/Er3+ pair, both displaying significant near-infrared emission. Isomorphous Na4[(Yb0.9Er0.1)2Ge4O13] features up-conversion emission, an unusual property among rare-earth crystalline germanates.
- Ananias, Duarte,Almeida Paz, Filipe A.,Carlos, Luís D.,Rocha, Jo?o
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- A new sol-gel route to synthesize YPO4:Tb as a green-emitting phosphor for the plasma display panels
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This work adopts a novel and low-cost sol-gel route to synthesize Tb 3+-doped YPO4 as a green-emitting phosphor for the plasma display panel (PDP). The phosphor obtained by this route shows improved luminescence efficiency in vacuum ultraviolet (VUV) excitation, compared with that obtained by a solid-state reaction. Copyright
- Di, Weihua,Wang, Xiaojun,Chen, Baojiu,Zhao, Xiaoxia
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- Monodisperse NaxY(OH)yF3+x-y Mesocrystals with tunable morphology and chemical composition: PH-Mediated ion-exchange
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This work reports self-Assembled uniform monodisperse NaxY(OH)yF3+x-y (0 a hydrothermal ionexchange reaction. Detailed crystal structure analysis illustrates that the special crystal structure of NaxY(OH)yF3+x-y (0 A possible topochemical-based mechanism has been proposed to this ion-exchange process. By carefully adjusting the pH value of the solution, the tunable three-dimensional (3D) NaxY(OH)yF3+x-y (0 3+, Tb3+, and Ce3+) doped as-prepared mesocrystal samples are investigated, and multicolor emissions are realized.
- Wang, Jiao,Liu, Bi-Qiu,Huang, Gaoshan,Zhang, Zhi-Jun,Zhao, Jing-Tai
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- Synthesis of nanocrystalline yttria doped ceria powder by urea-formaldehyde polymer gel auto-combustion process
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Nanocrystalline yttria doped ceria powder has been prepared by auto-combustion of a transparent gel formed by heating an aqueous acidic solution containing methylol urea, urea, cerium(III) nitrate and yttrium(III) nitrate. The TGA and DSC studies showed the combustion reaction of the gel initiated at 225 °C and completed within a short period of time. XRD spectrum of the combustion product reveals the formation of phase pure cubic yttria doped ceria during the combustion process. Loose agglomerate of yttria doped ceria particle obtained by the combustion reaction could be easily deagglomerated by planetary ball milling and the powder obtained contains particles in the size range of 0.05-3.3 μm with D50 value of 0.13 μm. The powder particles are aggregate of nanocrystallites with a wide size range of 14-105 nm. Pellets prepared by pressing the yttria doped ceria powder sintered to 95.2% TD at 1400 °C.
- Biswas,Prabhakaran,Gokhale,Sharma
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- Hydrothermal synthesis and characterization of Na3Y(PO 4)2 phosphate
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The Na3Y(PO4)2 phosphate has been obtained by hydrothermal route and characterized by powder XRD, differential scanning calorimetry/thermogravimetric analysis (DSC/TGA), SEM and FTIR spectroscopy. The effect of synthesis c
- Matraszek, Aleksandra,Szczygie?, Irena,Szczygie?, Bogdan
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- Emission Enhancement and Color Tuning for GdVO4:Ln3+ (Ln = Dy, Eu) by Surface Modification at Single Wavelength Excitation
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The surface modification can realize systematically the emission enhancement of GdVO4:Ln3+ (Ln = Dy, Eu) microstructures and multicolor emission at single component. The structure, morphology, composition, and the surface ligands modification of as-prepared samples were studied in detail. It is found that the surface-modified ligands can act as sensitizer to improve the emission of the Eu3+ and Dy3+ ions via the energy transfer besides the VO43--Eu3+/Dy3+ process. More importantly, under a single wavelength excitation, the emission color can be effectively tuned by manipulating the doping ratio of the Eu3+ ions in the internal crystal lattice and the Tb3+ ions in the external surface ligands, simultaneously. And further, multicolor emissions are obtained under single wavelength excitation due to the high overlapping between the VO43- absorption and the π-π? electron transition of the ligands. These findings may open new avenues to design and develop new highly efficient luminescent materials.
- Song, Yan,Shao, Baiqi,Feng, Yang,Lü, Wei,Huo, Jiansheng,Zhao, Shuang,Liu, Man,Liu, Guixia,You, Hongpeng
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- Synthesis, structure and magnetic properties of nanocrystalline YMnO 3
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Nanocrystalline YMnO3 has been prepared by wet chemical synthesis routes to obtain crystallites with sizes from 20 nm to bulk material. The crystal structure of hexagonal YMnO3 nanocrystallites smaller than 80 nm deviates from bulk material in terms of unit cell distortion and unit cell volume. The ferrielectric displacements of Y3+ cations along the polar c-axis decays progressively with decreasing size below 100 nm. Indications of weak ferromagnetism in the form of a narrow hysteresis loop and enhanced magnetic susceptibility below 43 K in 20 nm YMnO3 nanoparticles is attributed to extrinsic effects. Low-temperature annealing of the 20 nm crystallites in an oxidizing atmosphere removed all traces of ferromagnetism, showing that this is not a size-induced property. Finally, formation of the competing metastable orthorhombic phase and the thermodynamically stable hexagonal phase is discussed with respect to oxidizing or reducing conditions during synthesis. The Royal Society of Chemistry 2011.
- Bergum, Kristin,Okamoto, Hiroshi,Fjellvag, Helmer,Grande, Tor,Einarsrud, Mari-Ann,Selbach, Sverre M.
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- Europium-doped NaYF4 nanoparticles cause the necrosis of primary mouse bone marrow stromal cells through lysosome damage
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Applications of europium-doped NaYF4 (NaYF4:Eu3+) nanoparticles in biomedical fields will inevitably increase their exposure to humans, therefore, the assessment of toxicities must be taken into consideration. It was reported that NaYF4:Eu3+ nanoparticles could accumulate in the bone. However, the potential effect of NaYF4:Eu3+ nanoparticles on bone marrow stromal cells (BMSCs) has not been reported. In this study, NaYF4:Eu3+ particles with diameters of 50 and 200 nm (NY50 and NY200) were prepared and characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, photoluminescence excitation and emission spectra, and dynamic light scattering. The cytotoxicity of NaYF4:Eu3+ particles on BMSCs and the associated mechanisms were further studied. The results indicated that NaYF4:Eu3+ particles could be uptaken into BMSCs and primarily localized in the lysosome. NaYF4:Eu3+ particles effectively inhibited the viability of BMSCs in a size-dependent manner at 24 and 48 h. After cells were treated with 20 μg mL-1 of NY50 and NY200 for 24 h, NaYF4:Eu3+ particles could trigger cell necrosis in a size-dependent manner. The percentage of necrotic BMSCs (PI+/Annexin V-) increased to 15.93 and 14.73%. Necrosis was further verified by increased lactate dehydrogenase leakage. Meanwhile, both NY50 and NY200 induced an increased cell population in the S and G2/M phases. The following mechanism is involved in NaYF4:Eu3+ particle-induced BMSCs necrosis: the NaYF4:Eu3+ particles lead to lysosomal rupture by lysosomal swelling, permeabilization of lysosomal membranes, and increased cathepsins B and D. In addition, NaYF4:Eu3+ particle-induced BMSCs necrosis is also directly caused by the overproduction of ROS through injury to the mitochondria. This study provides novel evidence to elucidate the toxicity mechanisms for bone metabolism and may be beneficial to more rational applications of these nanomaterials in the future.
- Ge, Kun,Sun, Wentong,Zhang, Shaohan,Wang, Shuxian,Jia, Guang,Zhang, Cuimiao,Zhang, Jinchao
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- Photoluminescence efficiencies of nanocrystalline versus bulk Y 2O3: Eu phosphor-revisited
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Highly efficient yttrium oxide doped with trivalent europium (Y 2O3:Eu) phosphor was prepared through precursors synthesized by hydrothermal method. Crystalline precursors, namely europium-doped yttrium carbonate (Y2(COsu
- Paulraj, Arunkumar,Natarajan, Prabu,Munnisamy, Kottaisamy,Nagoor, Mujafar Kani,Parimana Nattar, Kamaraj,Abdulrazak, Burkanudeen,Duraisamy, Jeyakumar
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- Preparation and characteristics of core-shell structure Y 3Al5O12:Yb3+@SiO2 nanoparticles
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The club-shape (Y0.98Yb0.02)3Al 5O12 nanoparticles (YAG:Yb3+), which were synthesized by the co-precipitation method, had been successfully coated with silica from hydrolysis and condensati
- Sun, Yan-Hui,Yang, Zhong-Min,Xie, Cheng-Ning,Jiang, Zhong-Hong
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- Synthesis and multicolor upconversion of Tm3+/Er3+/Yb3+ doped Na (Y1.5Na0.5) F6 single-crystal nanorods
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Er3+/Tm3+/Yb3+ tri-doped Na (Y1.5Na0.5) F6 single-crystal nanorods were synthesized by a facile hydrothermal treatment method. The tri-doped sample was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). The sample showed a pure hexagonal phase structure with space group P63/m and nanorod morphology. Under 980 nm excitation, intense red, green and blue upconversion emissions were observed. The red and green upconversion are consistent with 4F9/2 → 4I15/2 and 2H11/2, 4S3/2 → 4I15/2 transition of Er3+, respectively, while the blue upconversion originates from 1G4 → 3H6 transition of Tm3+. Moreover, the Er3+/Tm3+/Yb3+ tri-doped Na (Y1.5Na0.5) F6 nanorods exhibit strong red and green emission which is ascribed to the sensitization of Tm3+ to Er3+. The energy transfer upconversion mechanisms for the fluorescent intensity are also discussed.
- Zeng, Songjun,Ren, Guozhong,Yang, Qibin
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- Site-Bi3+ and Eu3+ dual emissions in color-tunable Ca2Y8(SiO4)6O2:Bi3+, Eu3+ phosphors prepared via sol-gel synthesis for potentially ratiometric temperature sensing
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A series of Ca2Y8(SiO4)6O2 (CYSO):Bi3+, Eu3+ phosphors were prepared via a Pechini-type sol-gel reaction method. The refinement results for CYSO:Bi3+, Eu3+ phosphors implied that they had a pure phase. The blue-green emission ascribed to Bi3+ 3P1→1S0 transition was generated upon UV excitation in Bi3+ singly-doped CYSO samples. Spectral analysis indicated that two main emission bands around 414 and 494 nm correspond to two kinds of Bi3+ occupying the crystal lattices of 4f and 6 h available for Y3+ in CYSO, denoted as Bi3+(2) and Bi3+(1), respectively. A broad spectral overlap between Bi3+ emission and Eu3+ excitation spectra implied the existence of energy transfer from Bi3+ to Eu3+ ions in CYSO:Bi3+,Eu3+, which resulted in the tunable emission color from blue-green to red. The energy transfer mechanism from Bi3+ to Eu3+ ions was determined to be a dipole-quadrupole interaction. Moreover, the quite different luminescence thermal quenching behaviors between Bi3+(2) and Eu3+ showed good temperature sensing properties with a temperature range of 298–523 K by analyzing the temperature sensitivity of the fluorescent intensity ratio [Bi3+(2)/Eu3+(612)]. The maximum absolute and relative sensitivities reached as high as 0.07174 K-1 (523 K) and 0.958% K?1 (423 K), which can be compared to the highest values of 0.015 K-1 and 1.1%K?1 in reported optical thermometric materials before, respectively, based on the thermally coupled level (TCLs) of Er3+. Meanwhile, the luminescence thermal quenching mechanism in this system was investigated in detail. Results inspire that a feasible method based on site-Bi3+ and Eu3+ emissions is potential as one of candidate strategies for developing novel ratiometric optical thermometry materials.
- Li, Kai,Van Deun, Rik
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- Fabrication of oriented oxide films from exfoliated yttrium hydroxide layers: Enhanced photoluminescence and unexplored behavior of energy transfer
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Layered yttrium hydroxide (LYH) nanospalates doped with different activators (Tb3+ and/or Eu3+) were hydrothermally synthesized and then successfully delaminated into ultrathin nanosheets of down to 1–3 nm thickness via intercalation
- Huang, Junjie,Zhang, Tie,Ren, Ke,Zhang, Rui,Wu, Xiaoli,Li, Ji-guang
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- Host Differential Sensitization toward Color/Lifetime-Tuned Lanthanide Coordination Polymers for Optical Multiplexing
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Optical multiplexing based on luminescent materials with tunable color/lifetime has potential applications in information storage and security. However, the available tunable luminescent materials reported so far still suffer from several drawbacks of low efficiency or poor stability, thus restraining their further applications. Herein, we demonstrate a strategy to develop efficient and stable lanthanide coordination polymers (LCPs) with tunable luminescence as a new option for optical multiplexing. Their multicolor emission from green to red and naked-eye-sensitive green emission with tunable lifetime (from ca. 300 to ca. 600 μs) can be controlled by host differential sensitization and energy transfer between lanthanide ions. The quantum efficiencies of developed samples range from around 20 % to 46 % and the luminescence intensity/lifetime appear quite stable in polar solvents up to ten weeks. Furthermore, with the aid of inkjet printing and concepts of luminescence lifetime imaging and time-gated imaging, we illustrate their promising applications of information storage and security in spatial and temporal domains.
- Liang, Hongbin,Ma, Fengkai,Ma, Li,Ou, Yiyi,Su, Fang,Zheng, Lirong,Zhou, Rongfu,Zhou, Weijie,Zhu, Zece
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- Na(Y1.5Na0.5)F6:RE3+(Dy3+,Tb3+,Eu3+,Tm3+,Ho3+):Controllable morphology, multicolor light and thermal properties
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A series of emission-tunable Na(Y1.5Na0.5)F6: RE3+ (Dy3+,Tb3+, Eu3+, Tm3+, Ho3+) phosphors were firstly synthesized by the glycine assisted one-step hydrothermal process. The structure and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results revealed that the samples contain YF3 and Na(Y1.5Na0.5)F6 phases, and the size and shape of the products could be tuned just by adjusting the pH values of the initial reaction solutions or by adjusting the RE3+/NaF ratio or RE3+/NaBF4 ratio. The product morphologies include spindle-like microstructures, six prismatic, irregular microrods, micron hexagonal prisms and nano-spheres, micron elliptical disc, flower-like microstructures, spindle-like structures and irregular bulk. Furthermore, the photoluminescence properties of Na(Y1.5Na0.5)F6: RE3+ (Dy3+, Tb3+, Eu3+, Tm3+, Ho3+) were investigated in detail. Additionally, the emission color of Na(Y1.5Na0.5)F6: RE3+ (Dy3+, Tb3+, Eu3+, Tm3+, Ho3+) can be turned by adjusting the amount and kind of RE3+ ions. Importantly, the temperature-dependent photoluminescence of as-prepared phosphors was evaluated in detail. All these properties indicate that the developed phosphors may potentially be used as single-component multicolor-emitting phosphors.
- Guan, Hongxia,Li, Yunfei
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- Mutual solubility between hexane and tri-n-butyl phosphate solvates of lanthanide(III) and thorium(IV) nitrates at various temperatures
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The phase diagrams of binary liquid systems consisting of hexane and a tri-n-butyl phosphate (TBP) solvate of an Ln(III) (Ln = Nd, Gd, Y, Yb, Lu) or Th(IV) nitrate at various temperatures are considered. The diagrams show a field of homogeneous solutions and a two-phase field in which phase I is hexane-rich and phase II is rich in [Ln(NO3)3(TBP)3] or [Th(NO3)4(TBP)2]. The miscibility gap in the binary systems narrows with increasing temperature.
- Keskinov,Lishchuk,Pyartman
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- Structural, optical and special spectral changes of Dy3+ emissions in orthovanadates
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This paper reports on the structural, optical and photometric characterization of yttrium gadolinium orthovanadates (Y1-xGdxVO4) doped with Dy3+ for white emission in solid state lighting. A series of orthovanadates were prepared through a low temperature co-precipitation method and further post annealed. The as synthesized phosphor particles revealed a single phase tetragonal structure with space group I41/amd(141). The infrared spectra confirmed the presence of characteristic vibrational bands of orthovanadates. The microscopic images showed elongated particles after annealing and the particle sizes were estimated in the range of 10-50 nm. The band gap of the prepared phosphors, calculated from the corresponding diffuse reflectance spectra was observed to be 3.75 eV and 3.57 eV for YVO4 and GdVO4 respectively. Y1-xGdxVO4:Dy3+ phosphors, illuminated with ultraviolet light exhibited characteristic blue and yellow luminescence corresponding to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 transitions of Dy3+ ion. The emission spectra showed the variation in the intensity ratio (Y/B) with Gd3+ ion variation. Furthermore the thermal quenching property, decay analysis and photometric characterizations were also studied in detail and the results indicated the suitability of these phosphors in solid state lighting.
- Kumari, Puja,Manam
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p. 107575 - 107584
(2015)
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- Self-assembled three-dimensional NaY(WO4)2:Ln 3+ architectures: Hydrothermal synthesis, growth mechanism and luminescence properties
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Novel three-dimensional (3D) flower-like NaY(WO4) 2:Ln3+ (Ln = Eu, Yb/Er, Yb/Tm and Yb/Ho) microstructures with uniform shape and dimension have been prepared using Y(OH)CO3 nanospheres as sacrificial template through a hydrothermal process and followed by a subsequent heat treatment process. The whole process was carried out in aqueous condition without using any organic solvents, surfactant, or catalyst. The phase, morphology, size, and photoluminescence (PL) properties were well characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra, and kinetic decays, respectively. The results reveal that the as-prepared precursor of NaY(WO 4)2:Eu3+ exhibits interesting white light emission under UV excitation. After annealing, the as-obtained 3D flower-like NaY(WO4)2:Eu3+ microstructures show exclusively red (Eu3+, 5D0 → 7F 2) luminescence. Furthermore, the up-conversion (UC) luminescent properties and the emission mechanisms of NaY(WO4) 2:Yb3+/Ln3+ (Ln = Er, Tm, Ho) microstructures have been systematically studied, which show respective green (Er3+, 4S3/2, 2H11/2 → 4I15/2), blue (Tm3+, 1G4 → 3H6) and yellow-green (Ho3+, 5S2 → 5I8) luminescence under 980 nm NIR excitation.
- Huang, Shaohua,Wang, Dong,Wang, Yan,Wang, Liuzhen,Zhang, Xiao,Yang, Piaoping
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- Enhanced luminescence of novel Y2Zr2O 7:Dy3+ phosphors by Li+ co-doping
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Novel blue-white Y2Zr2O7:Dy3+, Li+ phosphors have been prepared by a facile and efficient sol-gelcombustion method at 800 °C, using ammonium nitrate as a fuel and citric acid as a complexing agent. No additional annealing was required, as crystalline Y2Zr2O7 resulted directly from the combustion reaction. The structure and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photoluminescence properties were measured using an Edinburgh FLS920 at room temperature. Stable blue-white emission from 425 nm to 625 nm has been observed from Y 2Zr2O7:Dy3+ and Y2Zr 2O7:Dy3+, Li+ phosphors. The optimal doping concentration of Dy3+ ions is 2 mol%. Experimental analysis and theoretical calculations reveal that the dipole-quadrupole (d-q) interaction should be the major concentration quenching mechanism of Dy3+ ions emission. Li+ co-doping improves luminescence intensity as well as crystallinity significantly. The incorporation of Li+ ions into Y2Zr2O7 lattice could induce a remarkable increase of photoluminescence intensity by about 2 times. The mechanism of the enhanced emission by Li+ doping was discussed. Both the chromaticity coordinates of Y2Zr2O7:Dy3+ and Y2Zr2O7:Dy3+, Li+ samples were in the near cold-white region.
- Du, Qingqing,Zhou, Guangjun,Zhou, Juan,Jia, Xiao,Zhou, Haifeng
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- Enhancing upconversion luminescence of highly doped lanthanide nanoparticles through phase transition delay
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Doping of rare earth (RE) ions in a low-phonon-energy host matrix is an effective strategy to enhance the upconversion luminescence (UCL) of lanthanide-doped nanoparticles. However, doping of optically inactive RE ions at high concentrations can cause an undesirable phase transition of the host matrix, with concomitant decrease in luminescence. Herein, we present a phase-transition-delay protocol to effectively preserve the pure orthorhombic phase of a KLu2F7:Yb3+,Er3+ system, even at high RE dopant concentrations. The proposed concept can be realized by incorporating a set of optically inactive RE dopants, i.e., Y3+ or Gd3+, with different ionic radii to replace the Lu3+ ions in the host matrix to overcome the energy barrier of the phase transition. The nanoparticles were synthesized in a high-boiling solvent or at a high reaction temperature. We observed maximal UCL of Er3+ at different Y3+ or Gd3+ dopant concentrations; the optimal Y3+ or Gd3+ concentration at which maximal UCL is observed is 10 mol% for samples prepared by a water-based hydrothermal route, while it is 30 mol% for samples prepared by an oleic acid-based hydrothermal route. Further, this optimal concentration could be increased to as much as 50 mol% by adopting a high reaction temperature. The high doping of Y3+ or Gd3+ can efficiently lead to enhanced upconversion performance of the final materials (as much as 32-fold and 9-fold enhancements in the upconversion intensity and quantum yield, respectively, are achieved). The UCL enhancement is caused by the break-down of the symmetry of lanthanide sites in the crystal lattice induced by Y3+ or Gd3+, which enhances the energy transfer probabilities between Yb3+ and Er3+. Our findings highlight a convenient route to simultaneously tune the phase transition of the host and upconversion output, and this strategy can be applied to other upconversion host materials.
- Xu, Dekang,Xie, Feiyan,Yao, Lu,Li, Yongjin,Lin, Hao,Li, Anming,Yang, Shenghong,Zhong, Shengliang,Zhang, Yueli
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- Controllable synthesis and tunable luminescence properties of Y 2(WO4)3:Ln3+ (Ln = Eu, Yb/Er, Yb/Tm and Yb/Ho) 3D hierarchical architectures
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Yttrium tungstate precursors with novel 3D hierarchical architectures assembled from nanosheet building blocks were successfully synthesized by a hydrothermal method with the assistance of sodium dodecyl benzenesulfonate (SDBS). After calcination, the precursors were easily converted to Y 2(WO4)3 without an obvious change in morphology. The as-prepared precursors and Y2(WO4) 3 were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra, respectively. The results reveal that the morphology and dimensions of the as-prepared precursors can be effectively tuned by altering the amounts of organic SDBS and the reaction time, and the possible formation mechanism was also proposed. Upon ultraviolet (UV) excitation, the emission of Y2(WO4)3:x mol% Eu3+ microcrystals can be tuned from white to red, and the doping concentration of Eu3+ has been optimized. Furthermore, the up-conversion (UC) luminescence properties as well as the emission mechanisms of Y2(WO4) 3:Yb3+/Ln3+ (Ln = Er, Tm, Ho) microcrystals were systematically investigated, which show green (Er3+, 4S3/2, 2H11/2 → 4I15/2), blue (Tm3+, 1G4 → 3H6) and yellow (Ho3+, 5S2 → 5I8) luminescence under 980 nm NIR excitation. Moreover, the doping concentration of the Yb3+ has been optimized under a fixed concentration of Er3+ for the UC emission of Y2(WO4)3:Yb3+/Er 3+.
- Huang, Shaohua,Zhang, Xiao,Wang, Liuzhen,Bai, Ling,Xu, Jie,Li, Chunxia,Yang, Piaoping
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- The sorption properties of carbon nanotubes modified with tetraphenylmethylenediphosphine dioxide in nitric acid media
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The distribution of microamounts of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous solutions of HNO3 and multiwalled carbon nanotubes noncovalently modified with tetraphenylmethylenediphosphine dioxide (L) wa
- Turanov,Karandashev,Evseeva,Kolesnikov,Borisenko
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- The effects of Gd3+ substitution on the crystal structure, site symmetry, and photoluminescence of Y/Eu layered rare-earth hydroxide (LRH) nanoplates
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Well crystallized nanoplates of the (Y0.95-xGd xEu0.05)2(OH)5NO3· nH2O ternary layered rare-earth hydroxides (LRHs), synthesized hydrothermally, have been investigated with emphasis on the effects of Gd 3+ substitution for Y3+ on the structural features and optical properties. Characterizations of the materials were achieved by the combined techniques of XRD, FT-IR, TEM, DTA/TG, and optical spectroscopies. The results showed that Gd3+ substitution leads to linearly expanded ab plane, shortened interlayer distance (c/2), and reduced hydration (smaller n value) of the crystal structure. As a consequence, the Ln3+ partially shifts from the C4v to C1 site symmetries and thus leads to systematically altered photoluminescence behaviors. Under the 7F0→5L6 transition excitation of Eu3+ at 394 nm, both the 5D0→ 7F2 to 5D0→7F 4 and the 595 nm 5D0→7F 1 to 590 nm 5D0→7F1 intensity ratios linearly increase towards a higher Gd3+ content. The incorporated Gd3+ cations selectively sensitize emission from the C1-site Eu3+ and produce a new charge transfer (CT) excitation band at ~254 nm. With this, the desired 615-nm red emission is obtainable either under intra-4f6 transition excitation of Eu 3+ or by exciting the CT band. The materials have similar fluorescence lifetimes of 0.85 ± 0.05 ms for the 615-nm emission, irrespective of the Gd3+ content and excitation wavelength.
- Wu, Xiaoli,Li, Ji-Guang,Zhu, Qi,Li, Jinkai,Ma, Renzhi,Sasaki, Takayoshi,Li, Xiaodong,Sun, Xudong,Sakka, Yoshio
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- Multiple ratiometric nanothermometry operating with Stark thermally and non-thermally-coupled levels in upconverting Y2?xMoO6:xEr3+ nanoparticles
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Contactless optical nanothermometers of high thermal sensitivity are in great demand in various fields. In this work, we applied a facile sol-gel method to synthesize a series of Y2-xMoO6:xEr3+ upconverting nanoparticles (UCNPs), capable of acting as luminescence nanothermometers. Upon 980 nm laser light irradiation, with increasing Er3+ content, the prepared samples show a color-tunable upconversion emission, from green to yellow. Comparison of the thermometric properties determined by the Stark thermally coupled levels (TCLs) with those determined by the Stark non-thermally coupled levels (non-TCLs) showed that the superior thermal sensitivity (maximal Sr = 2.063%K?1 at 303 K) is achieved for the non-TCLs 4F9/2(1)/4S3/2(1). Moreover, a higher content of Er3+ in UCNPs (Y1.88MoO6:0.12Er3+ UCNPs) has been found to lead to a significant increase of Sr (Sr MAX = 2.460%K?1 at 303 K). Y2-xMoO6:xEr3+ UCNPs are promising materials for contactless nanothermometers of high sensitivity.
- Zheng, Teng,Qiu, Xujun,Zhou, Luhui,Runowski, Marcin,Lis, Stefan,Du, Peng,Luo, Laihui
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- Comparative study on the morphology, growth mechanism and luminescence property of RE2O2S:Eu3+ (RE = Lu, Gd, Y) phosphors
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The rod-like Lu2O2S:Eu3+, cylindrical Gd2O2S:Eu3+ and irregular Y2O2S:Eu3+ with long slice structure were obtained by solvothermal synthesis and subsequent calcination process. Aggregation, self-assembly, and crystal growth are considered to be the main formation processes of precursor sample. The specific growth process of different morphologies was discussed and analyzed in details. The results show that under the condition of high pH value, matrix cation has a great effect on morphology control. X-Ray diffraction tests and Rietveld refinement analysis method were performed on RE2O2S:Eu3+ phosphor powders (RE=Lu, Gd, Y) for evaluating the structural properties of the samples. Fluorescence study was used to analyze the luminescence properties of RE2O2S:Eu3+. It can better maintain the luminescence intensity at about 50% of room temperature at 300 K through the variable temperature emission spectrum test. It can be seen from the spectral coordinate changes that the color stability of the sample is good, which may have potential application value in the field of luminescence.
- Qian, Benfu,Wang, Ze,Wang, Yulu,Zhao, Qianran,Zhou, Xiuqing,Zou, Haifeng,Song, Yanhua,Sheng, Ye
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- Generalized synthesis of NaLn(MoO4)2 nano/microcrystals (Ln = La–Lu and Y): The effects of lanthanide contraction, structure, and down-/up-conversion luminescence
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Systematic synthesis of scheelite-type double molybdate nano-/microcrystals NaLn (MoO4)2 (Ln = La–Lu lanthanides and Y) was successfully carried out via hydrothermal reaction at 180 °C without using any organic additive, and the intrinsic effects of lanthanide contraction on phase preference and crystallite morphology were unambiguously observed. It was shown that the products of larger Ln3+ (Ln = La–Dy) and smaller Ln3+ (Ln = Ho–Lu and Y) elements crystallized as tetragonal NaLn (MoO4)2 and new orthorhombic NaLnMo2O8·2H2O structures, respectively, with the latter being able to dehydrate to tetragonal NaLn (MoO4)2 upon calcination at ~300 °C. Y was found to be a demarcation point for the two structures, and phase preference was shown to be influenced by solution pH and MoO42?/Y3+ molar ratio. With Eu3+ as a downconversion (DC) luminescence probe, the effects of Ln type (Ln = La, Gd, Y and Lu) and crystal structure were manifested. Furthermore, the upconversion (UC) luminescence of Yb3+/Ho3+ and Yb3+/Er3+ pairs in NaLu(MoO4)2 was studied for the first time, and strong red and green UC emissions were observed under the 978 nm laser excitation. Besides, the processes/mechanisms of UC were studied via varying the excitation power and were discussed with Yb3+-MoO42- dimer sensitizer.
- Li, Ji-Guang,Li, Siyuan,Meng, Qinghong,Wang, Xuejiao,Xu, Zhixin,Zhu, Qi
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- Study of energy transfer from Bi3+ to Tb3+ in Y2O3 phosphor and its application for W-LED
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Y2O3 activated with different activators were prepared by co-precipitation method. The prepared phosphors were characterized by XRD, SEM and photoluminescence (PL) techniques. The Tb3+ doped Y2O3 phos
- Taikar, D. R.
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- A new protocol for templated synthesis of YVO4:Ln luminescent crystallites (Ln=Eu, Dy, Sm)
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RE(OH)2.94(NO3)0.06·nH2O nanosquares were first employed as template to synthesize YVO4:Ln luminescent crystallites (Ln = Eu, Sm, and Dy) via hydrothermal nanoconversion in the presence of NH4VO3. Product properties and the course of phase/morphology evolution were characterized in detail by XRD, SEM, TEM, FT-IR, TG, and optical spectroscopy. It was clearly demonstrated that the nanosquares templated vanadate crystallization, owing to structure similarity, but was accompanied by subsequent dissolution and reprecipitation. The resultant vanadate phosphors, mostly in the form of bundles containing platelike and fibrous crystallites, exhibited strong red emission at ~618 nm for Eu3+, orange-red emission at ~604 nm for Sm3+ and greenish yellow emission at ~575 nm for Dy3+ upon exciting the VO43? ligand. Dehydration at 500 °C further improved the emission by ~2.5 times for Eu3+ and ~1.5 times for Sm3+ and Dy3+. The Eu3+ (5 at%), Sm3+ (1 at%) and Dy3+ (1 at%) activators were analyzed to have quantum yields of ~48, 9 and 16% and color coordinates of around (0.65, 0.33), (0.60, 0.39) and (0.38, 0.43) for their luminescence, and fluorescence lifetimes of ~1.52, 1.40 and 0.89 ms for their dominant emissions, respectively. It is also interesting to find out that replacing only 15% of the total OH? and NO3? anions in the template by VO43? produced ~20 times stronger Eu3+ luminescence, indicating that VO43-→ Eu3+ energy transfer is very efficient. The protocol would be extendable to other types of functional rare-earth compounds.
- Huang, Sai,Wang, Zhihao,Zhu, Qi,Shi, Xiaofei,Wang, Xuejiao,Li, Xiaodong,Sun, Xudong,Li, Ji-Guang
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p. 773 - 781
(2018/11/06)
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- An l-cysteine-mediated iodide-catalyzed reaction for the detection of I-
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In this study, a highly selective and eco-friendly fluorescent sensor consisting of upconversion (UCNPs) and gold nanoparticles (AuNPs) was developed for the detection of iodide (I-). The negatively charged AuNPs were able to electrostatically adsorb on the positively charged UCNPs, leading to the fluorescence quenching of the UCNPs. In the presence of l-cysteine, AuNPs were released from the surface of the UCNPs and aggregated due to the Au-S interactions that occurred between the AuNPs and l-cysteine, which resulted in the fluorescence recovery of the UCNPs. Upon the addition of I-, the fluorescence of the UCNPs was gradually quenched meaning that I- catalyzes the oxidation of l-cysteine, preventing the aggregation of AuNPs and forming a fluorescence resonance energy transfer system. The I--catalyzed oxidation reaction provides a method for the l-cysteine-triggered sensor to detect I-, using l-cysteine to modulate the fluorescence signal in an eco-friendly manner. Based on the above special detection strategies, this sensor has excellent selectivity for I- even in a complex matrix such as urine, which is much better than most assays for I-. Under the optimal conditions, the sensor allows the quantitative analysis of I- with a detection limit of 55 nM. The high selectivity, sensitivity and environmental friendliness of the sensor proves that it has the potential for the detection of I- in actual samples. Most importantly, the excellent results of the sensor for the detection of I- in urine prove that the probe can be used as an ideal tool in clinic diagnoses.
- He, Kaili,Chen, Hongyu,Wu, Cuiyan,Liu, Meiling,Zhang, Youyu
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p. 1398 - 1403
(2019/01/21)
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- Preparation and characterization of a new series of solid solutions of Bi1?xYxFeO3 (0 < x < 1) from the thermal decomposition of hexacyanoferrates doped with yttrium
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Solid solutions of Bi1?xYx[Fe(CN)6]·4H2O (0 3+ by Y3+ was appropriately materialized. The thermal behavior was studied by thermogravimetric and differential thermal analysis. A single phase of perovskite-type Bi1?xYxFeO3 powders was obtained by thermal decomposition of the complexes at about 600?°C. The obtained products were identified and characterized by energy-dispersive spectroscopy, Raman and Fourier transform infrared spectroscopy and powder X-ray diffraction. The size and morphology of the complexes and their thermal decomposition products were evaluated by scanning electron microscopy. Thermal analysis showed that the complexes were good intermediaries for the synthesis of high-purity mixed oxides with a uniform particle size of the order of nanometers. To evaluate the effect of doping with yttrium, electrical transport measurements were performed.
- Runco Leal, Verónica,Navarro, Carolina,Bridoux, Germán,Villafuerte, Manuel,Gómez, María Inés
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p. 3259 - 3268
(2018/08/25)
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- Fabrication of (Y0.95Eu0.05)2O3 phosphors with enhanced properties by co-precipitation of layered rare-earth hydroxide
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This work is devoted to a simple method for synthesizing phosphors based on layered rare earth hydroxonitrates (LRH). Layered precursors of (Y0.95Eu0.05)2(OH)5(NO3)·xH2O with different morphologies were obtained via co-precipitation at a constant pH and hydrothermal methods. It was established that LRHs co-precipitated at pH 7 are highly ordered close-packed micron-sized plates with low porosity. With an increase in the pH of co-precipitation to 9.5, the phase composition is retained, but the isotropy and porosity of the particles increases sharply: the morphology changes from micron flat plates to curved nanosheets and nanoflakes. Co-precipitated LRHs crystallize more intensively into cubic (Y0.95Eu0.05)2O3 during heat treatment compared to precursors obtained under mild hydrothermal conditions (120 °C, 24 h). The structural characteristics of the material laid at the stage of synthesis directly determine its optical properties and the fundamental parameters of photoluminescence. The phosphors that co-precipitate at pH 7 demonstrate the highest yield of luminescence due to a more ordered structure, larger crystallite size, lower asymmetry factor and surface to volume ratio. The proposed co-precipitation method with a constant pH value of 7 allows one to obtain (Y0.95Eu0.05)2O3 phosphor with enhanced structural and optical properties compared to materials synthesized in hydrothermal conditions. The LRHs co-precipitated in this work are a promising precursor for the preparation of crystal-oriented and highly-efficient luminescent coatings and nanofilms.
- Aleshin, Danil K.,Mashkovtsev, Maxim A.,Kuznetsova, Yulia A.,Rychkov, Vladimir N.,Zatsepin, Anatoly F.,Gordeev, Egor V.
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p. 258 - 266
(2019/07/16)
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- Synthesis, optical properties and application of Y7O6F9:Er3+ for sensing the chip temperature of a light emitting diode
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Submicron-sized Er3+ doped Y7O6F9 phosphors were synthesized via the precipitation method and a subsequent annealing process. The influence of the Er3+ doping concentrations and the heating temperature on the luminescence of Y7O6F9:Er3+ was investigated under the excitation of the Er3+ 4G11/2 level at 378 nm. Upon raising the Er3+ doping concentration, both the intensity and lifetime of the Er3+ green emission at 547 nm originating from 4S3/2 → 4I15/2 decrease, which is proved to be caused by energy transfer via cross relaxation between two neighboring Er3+ ions. The thermal sensing properties of Y7O6F9:Er3+ were evaluated using the temperature dependent intensity ratio between the 2H11/2-4I15/2 and 4S3/2-4I15/2 transitions of Er3+ under 378 nm excitation. The experimental results show that the thermal sensitivity decreased with an increase in the Er3+ doping content, which is caused by the increased energy transfer probability among Er3+. The increased energy transfer of Er3+ reduces the thermalized population of Er3+ in the 2H11/2 levels, which in turn decreases the thermal sensitivity. The applicability of Er3+ doped Y7O6F9 as a thermal sensor was demonstrated by measuring the chip temperature of a 1 W InGaN type near-ultraviolet light emitting diode (n-UV LED).
- Wang, Deyin,Zhang, Pengpeng,Ma, Qiang,Zhang, Jiachi,Wang, Yuhua
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p. 13352 - 13358
(2019/01/03)
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- Spherical engineering and space-group dependent luminescence behavior of YBO3:Eu3+ red phosphors
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Spherical particles of (Y1-xEux)BO3 (x = 0–0.20, ~0.8–1.5 μm in diameter) have been converted from (Y1-xEux)(B(OH)4)CO3 precursors synthesized via homogenous precipitation processing. Detailed characterizations of the samples were achieved by combined techniques of XRD, Raman, FE-SEM, HR-TEM, PLE/PL, and fluorescence decay analysis. Through homogenous precipitation processing in the absence of EG, orthorhombic (Y,Eu)(B(OH)4)CO3 cubic particles were obtained owing to their crystal habit. Proper EG addition leads to the formation of spherical particles, but nano-sized amorphous particles were resulted from the excessive EG content. Longing reaction time or elevating the reaction temperature induced the appearance of cubic ones. Calcining (Y,Eu)(B(OH)4)CO3 at 700 °C yielded hexagonal structured (Y,Eu)BO3 phase with the space group of P63/m, but another hexagonal structured (Y,Eu)BO3 phase (space group: P63/mmc) was obtained with the calcination temperatures of 800–1000 °C. The spherical shape and excellent dispersion of the original particles can be well retained up to 800 °C. Upon UV excitation, the (Y1-xEux)BO3 (x = 0–0.20) spheres exhibited a typical Eu3+ emission with the orange emission at 592 nm from the 5D0-7F1 magnetic dipole transitions of Eu3+ ions taking the dominant role. Space-group vibrations between in 700 °C-phase and 800–1000 °C phase resulted in the blue shift of CTB center, but they did not significantly affect the lifetimes. A higher Eu content (x = 0.01–0.10) leaded more Eu3+ ions occupying the non-centrosymmetric site instead of S6 one, thus inducing enhanced emission of 5D0→7F2 transition, larger asymmetry factor, and red shift of the CIE chromaticity coordinates. However, the asymmetry factor remains nearly constant with the x value up to 0.20. The fluorescence lifetime is similar (5.3 ± 0.3 ms) up to 8 at% of Eu3+, followed by decreases at higher Eu3+ contents.
- Zhu, Qi,Wang, Shuo,Li, Ji-Guang,Li, Xiaodong,Sun, Xudong
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p. 1069 - 1079
(2017/10/30)
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- Effect of Nano-Sized Y2O3 Doping on the Electrical Properties of (Ba0.90Ca0.10)(Ti0.9Sn0.1)O3 Ceramics
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Well dispersed Y2O3 nanoparticles are prepared by azeotropic co-precipitation method. (Ba0.90Ca0.10)(Ti0.9Sn0.1)O3 lead-free piezoelectric ceramics doped with the nano-sized Ysu
- Chen, Zhi-Hui,Li, Zhi-Wei,Qiu, Jian-Hua,Zhao, Tian-Xiang,Zhu, Ke-Qin,Ding, Jian-Ning,Zhu, Wei-Qin,Xu, Jiu-Jun
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- Fabrication of highly porous Y2O3:Ho,Yb ceramic and its thermometric applications
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Highly porous Y2O3:Ho,Yb ceramic with relative high compressive strength was successfully fabricated by using NaF as pore-forming agent for the first time. The porosity, pore size, compressive strength and temperature-dependent upcon
- Guo, Yanyan,Wang, Dianyuan,He, Yong
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p. 1158 - 1162
(2018/02/10)
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- Structural and electrical conduction behaviour of yttrium doped strontium titanate: anode material for SOFC application
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Yttrium (Y3+) doped strontium titanate (YxSr1-xTiO3-δ with x = 0, 0.03, 0.05, 0.08 and 0.10) was synthesized via citrate-nitrate auto-combustion route. The electrical and structural properties of the prepared compositions were investigated to check their suitability as anode material for SOFC application. The XRD patterns of synthesized specimens showed single phase having a crystal structure similar to that of the undoped SrTiO3. Trace amounts of secondary phase were observed in compositions with x ≥ 0.05. The FESEM micrographs of all compositions revealed a non-monotonous behaviour of grain size in YxSr1-xTiO3 system with YST8 as most porous sample among all prepared compositions. The oxygen content in the specimens was also confirmed through XPS analysis. The conductivity values in air and H2 atmosphere were obtained from Nyquist plots in the temperature range of 100–700 °C. From a systematic study, the conduction mechanism was explained on the basis of defect chemistry. Moreover, the chemical stability of samples was checked through XRD patterns with corresponding FESEM micrographs after the conductivity measurements in H2 atmosphere. Results showed that amongst all the prepared samples, Y0.08Sr0.92TiO3 may be proposed as a promising composition as anode material for SOFC application.
- Singh, Saurabh,Jha, Priyanka A.,Presto, Sabrina,Viviani, Massimo,Sinha,Varma, Salil,Singh, Prabhakar
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p. 637 - 644
(2018/03/24)
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- Luminescent Thermometry by a Y/Eu Binary Layered Rare-Earth Hydroxide (LRH) via In Situ Intercalation with Neutral Terbium(III) Complexes
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Temperature-sensitive luminescent materials have aroused great interest for practical applications in optical sensors. Layered rare-earth hydroxides (LRHs) possess rich interlayer chemistry and adjustable composition; thus, they are the promising candidates for designing functional materials, usually through an ion exchange process. Herein, the intercalation of neutral TbIII complex rather than ion exchange was successfully performed in situ into the gallery of Y/Eu binary LRHs by using a hydrothermal process. Interestingly, the swollen LRHs are chameleon luminophores, exhibiting color emissions from green to pink that were tunable through variations in temperature ranging from 77 to 450 K. Because of the highly sensitive and temperature-dependent emissions, novel optical temperature sensors for 1D and 2D thermal imaging were fabricated by employing the chameleon luminophores, which displayed luminescence capable of reversibly undergoing repeated thermocycles. The present work opens up new fields in layered inorganic materials.
- Zhu, Qi,Li, Siyuan,Jin, Jianfeng,Xu, Zhixin,Li, Xiaodong,Sun, Xudong,Li, Ji-Guang
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supporting information
p. 3664 - 3669
(2018/10/31)
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- Effect of yttrium doping on structure, magnetic and electrical properties of nanocrystalline cobalt ferrite
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Tailoring of properties by changing morphology or by doping is very much required for the suitable application of any materials. Here we report the effect of yttrium doping on microstructure, magnetic and electrical properties of cobalt ferrite nanoparticles prepared through citrate auto-ignition method. Rietveld refinement analysis of X-ray diffraction pattern confirms the growth of pure and single phase cobalt ferrite nanoparticles which corroborates with transmission electron microscopy (TEM) study. Microstructural parameters, obtained from Rietveld analysis showed that oxygen vacancy is maximum and inter-ionic bond lengths and bond angles attain optimum values for 15 mol% yttrium doped sample. An observed value of saturation magnetization indicates the existence of spin canting phenomenon which was explained by Yafet-Kittel model. Magnetic parameters such as anisotropy constant, anisotropy field have been estimated using Law of Approach (L.A.) formalism. Existence of interparticle dipolar interaction (IPDI) in the system was established with the help of Mr/Ms ratio around room temperature. Maximum electrical conductivity has been observed for the 15 mol% doped sample as estimated from Mott's 3-D V.R.H. model, which can be attributed to the optimum values of microstructural parameters at this composition.
- Chakrabarty,Dutta,Pal
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- Effect of silica coating on luminescence and temperature sensing properties of Nd3+ doped nanoparticles
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Structural and luminescence properties of uncovered YVO4:Nd3+ and core-shell YVO4:Nd3+@SiO2 nanoparticles synthesized via modified Pechini technique were studied. Effect of silica shell thickness on steady state and kinetics luminescence parameters was investigated. Synthesized nanoparticles were used as non-contact optical thermometers operating in the second biological window upon heating-free 808 nm light by monitoring fluorescence intensity ratio between Nd3+ emission bands as a temperature-dependent parameter. Benefits of silica coating on the temperature sensing properties were clearly demonstrated. The best thermal sensitivity was found to be 0.40% K?1 at 299 K, the minimum temperature uncertainty was less than 0.5 K, which is enough for accurate temperature evaluation in the real systems.
- Kolesnikov,Kurochkin,Kalinichev,Mamonova,Kolesnikov, E. Yu.,Kurochkin,L?hderanta,Mikhailov
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p. 136 - 143
(2017/11/15)
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- Y2Si4N6C:Ce3+ carbidonitride green-yellow phosphors: Novel synthesis, photoluminescence properties, and applications
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The Y2Si4N6C:Ce3+ carbidonitride phosphor has been successfully synthesized via a novel acid-driven carbonization and carbothermal reduction nitridation method (ADC-CRN). This novel approach for Y2Si4N6C:Ce3+ promises lower heating temperature and shorter heating time than classical methods, indicative of a cost-effective and facile way to search for new silicon-based carbidonitrides. In contrast to Ce3+ activated (oxy)nitrides showing blue-green emissions, Y2Si4N6C:Ce3+ exhibits an individual green-yellowish emission band centered at 550 nm which is ascribed to the incorporation of highly covalent C4- into the host lattice. The sp3 hybrid C4- was identified through high resolution electron energy loss spectroscopy analysis (EELS). Direct evidence for sole substitution of Ce3+ for Y3+ in Y2Si4N6C is represented for the first time using electron paramagnetic resonance (EPR) spectra. The red shift induced by the increasing Ce3+ content in Y2Si4N6C is reasonably deduced by the energy transfer model of intra-Ce3+ and inter-Ce3+ ions. A pc-w-LED packaging was fabricated via a combination of the yellow Y2Si4N6C:Ce3+ and blue La2Si4N6C:Ce3+ phosphors prepared using a 365 nm n-UV chip. The w-LED device shows a good color rendering index (Ra), CIE chromaticity coordinates and correlated color temperature (CCT) of 83.8, (0.3258, 0.3314) and 5819 K, respectively. These results suggest that Y2Si4N6C:Ce3+ has great potential for use in UV-LED-driven white emitting diodes.
- Wan, Jieqiong,Liu, Qian,Liu, Guanghui,Zhou, Zhenzhen,Xie, Rong-Jun
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p. 6061 - 6070
(2017/07/10)
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- Tuning the Energy Transfer Efficiency between Ce3+and Ln3+Ions (Ln=Tm, Sm, Tb, Dy) by Controlling the Crystal Phase of NaYF4Nanocrystals
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NaYF4is a superior host matrix to study the luminescence properties of lanthanide (Ln3+) ions. Ln3+ions in hexagonal-phase NaYF4(β-phase) nanocrystals (NCs) exhibit strong luminescence via an upconversion process compared to cubic NaYF4(α-phase) NCs. However, in Ce3+/Ln3+-doped NaYF4NCs (Ln=Tm, Tb, Sm, Dy) the α-phase NaYF4NCs shows strong luminescence compared to their counterpart β-phase NCs despite the latter being much larger in size. This is attributed to comparatively large overlap between Ce3+ions emission band with excited energy levels of those Ln3+ions in α-phase compared to β-phase NCs. This difference is attributed to different crystal-field splitting of Ce3+ions 4f–5d band in different crystal environments of the α-phase (cubic crystal field environment) and β-phase (trigonal prismatic with equatorials crystal field environment) NaYF4NCs with respect to their barycenter. The enhanced luminescence from α-phase NaYF4NCs is advantageous as they are prepared at a relatively lower temperature and shorter reaction times compared to β-NaYF4NCs.
- Adusumalli, Venkata N. K. B.,Koppisetti, Heramba V. S. R. M.,Ganguli, Sagar,Sarkar, Shyam,Mahalingam, Venkataramanan
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p. 994 - 1000
(2017/02/05)
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- Influence of Au nanoparticles on luminescence property of YF3 submicrostructures doped with Yb3+ and Ho3+ (Eu3+) ions
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Orthorhombic phase YF3 submicrostructures doped with Yb3+ and Ho3+ (Eu3+) ions (YF3:RE3+ (RE3+?=?Yb3+, Ho3+ (Eu3+)) submicrostructures) were synthesized by a coprecipitation method and decorated with Au nanoparticles (NPs) to form hybrid submicrostructures. It was found that the attached Au NPs on the surfaces of YF3:RE3+ submicrostructures could generate localized electromagnetic (EM) field with high density, which enable the enhancement of upconversion luminescence emission of YF3:RE3+. The luminescence emission of Eu3+ ion was employed to investigate the local symmetry change of YF3:RE3+ after Au NPs were introduced to the system. The possible mechanism of Au NPs on the luminescence property of doped rare earth (RE) ions was proposed and discussed. These submicrostructures may find potential applications in phosphors and solar cells.
- Han, Qingyan,Yan, Longxiang,Zhang, Chengyun,Zhang, Mindi,Zhang, Tingting,Zheng, Hairong
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p. 322 - 328
(2017/05/10)
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- Enhanced emission of Tm3+:3F4?→?3H6 transition by backward energy transfer from Yb3+ in Y2O3 for mid-infrared applications
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Tm3+ doped luminescence materials have attracted great attention owing to their potential for achieving 2 μm laser. Here, we report that the 2 μm emission intensity of Tm3+:3F4 → 3H6 transition can be enhanced by as large as 1.8 times through introducing Yb3+ into Tm3+ doped Y2O3 upon 782 nm excitation, where the population of Tm3+:3F4 level is increased by backward energy transfer from Yb3+ following the forward energy transfer from the upper level Tm3+:3H4 to an intermediate level Yb3+:2F5/2. In addition, the efficiencies of Yb3+ to Tm3+ backward energy transfer are determined based on the analysis of emission spectra and fluorescence time profiles. It is found that the Yb3+ to Tm3+ backward energy transfer upon Tm3+ excitation at 782 nm is more efficient than the Yb3+ to Tm3+ energy transfer upon Yb3+ direct excitation at 980 nm, which is explained by the preferential excitation of Yb3+ with a nearby Tm3+ in the forward energy transfer from Tm3+ to Yb3+ upon Tm3+ excitation. Our results demonstrate that codoping Yb3+ into Tm3+ activated materials offers a promising approach to obtain efficient 2 μm laser, and the efficient backward energy transfer may play a key role in other rare earth ions doped luminescence materials.
- Wu, Dan,Xiao, Wenge,Zhang, Xia,Hao, Zhendong,Pan, Guo-Hui,Zhang, Liangliang,Luo, Yongshi,Zhang, Jiahua
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- Spectroscopic studies of noble metal incorporated lanthanide vanadates and YF3:Tb3+ nanoclusters encapsulated in hybrid hydrogels
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Extensive analysis of europium doped yttrium vanadate (YVO4: Eu3+) and terbium doped yttrium fluoride (YF3:Tb3+) has been evaluated by means of powder X-ray diffractions, scanning electron microscope and luminescence spectroscopy techniques. The results demonstrate noticeable difference in emission spectra for the sample of YVO4: Eu3+ in the presence of Gd3+. As for the influence of the nanocrystal surface, the incorporation of silver content will also affect the intensity of the europium(III) luminescence. In addition, a hydrolytic sol-gel approach and a soft support matter (polyacrylic acid) were employed for the fabrication of YF3:Tb3+ activated hydrogel. The emission spectra gave rise to the intensive green emissions centered at 545 nm due to 5D4→7F5 transition of Tb3+. Temperature elevation experiments were performed and could partially recover the green emissions.
- Zheng, Yuhui,Jiang, Chunxia,Huo, Jiansheng,Hu, Jing,Gao, Jinwei,Lu, Xubing,Rao, Shuangyue,Zeng, Zhi,Wang, Qianming
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p. 1142 - 1147
(2017/09/05)
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- Fabrication of core@spacer@shell Aunanorod@mSiO2@Y2O3:Er nanocomposites with enhanced upconversion fluorescence
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Herein, we report the fabrication of well-defined Aunanorod@mSiO2@Y2O3:Er nanocomposites with a Au nanorod core, an Y2O3:Er shell, and mesoporous silica as spacer. The thickness of the mesoporous silica layer could be simply controlled by varying the reaction time and the amount of silica precursor. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy and UV-vis absorption spectroscopy. Thanks to the two distinct plasmon absorptions of the Au nanorod associated with the longitudinal and transverse surface plasmon resonances modes, the plasmon resonances matched very well to the absorption and emission wavelengths of Y2O3:Er in the near IR and visible regions, respectively. The strongest enhancement is observed when the optimized silica thickness is around 40 nm, resulting in about 10- and 8-fold enhancement for green and red emissions, respectively. Besides the enhanced upconversion fluorescence, the prepared nanocomposites with unique properties and functions offered by Au nanorod and mesoporous silica structure are expected to be useful in photothermal therapy, drug delivery, medical diagnostics and therapy.
- Li, Huiqin,Deng, Qingqing,Liu, Bin,Yang, Jianhui,Wu, Biao
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p. 13343 - 13348
(2016/02/12)
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- Ionic conductivity of Nd3+ and Y3+ co-doped ceria solid electrolytes for intermediate temperature solid oxide fuel cells
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Nanocrystalline co-doped ceria powders having composition, Ce0.80Nd0.20-xYxO1.90 has been prepared via citrate/nitrate gel auto-combustion method. Phase identification, surface morphology and electrical measurem
- Kobi, Sushobhan,Jaiswal, Nandini,Kumar, Devendra,Parkash, Om
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p. 513 - 519
(2015/11/25)
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- Novel fabrication, microstructure and upconversion photoluminescence properties of Tm3+, Yb3+co-doped Y2O3translucent ceramics
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A novel fabrication of Y2O3:Tm,Yb translucent ceramics by sintering method using synthetic YF3:Tm,Yb microtube powders was reported for the first time. The experimental results showed that the full dense microstructure could be obtained with grain size of about 2?μm. The obtained Y2O3:Tm,Yb ceramics had less pores and high optical transparency. By using a 980?nm diode laser as the pumping source, the Y2O3:Tm,Yb ceramics gave intense blue and red upconversion luminescence emissions, which were ascribed to the radiative transitions of1G4→3H6,1G4→3F4and3F2,3?→?3H6of Tm3+ions, respectively. The dependence of upconversion emission intensity on the excitation power was examined, and the possible upconversion mechanisms had been proposed accordingly.
- Guo, Yanyan,Wang, Dianyuan,Wu, Xinghua,Wang, Qingkai,He, Yong
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p. 816 - 819
(2016/07/21)
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- Tb-doped YPO4phosphors: Polyacrylamide gel synthesis and optical properties
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Single phase of Tb-doped YPO4phosphors with xenotime structure were successfully synthesized via a polyacrylamide gel at different annealing temperatures (650–1050?°C). The crystal structure, thermal behavior and optical properties of the as-synthesized samples were investigated by XRD, TG-DTA, FT-IR, PL, and XPS. The effects of heat treatment on the structure and luminescence properties of samples were discussed. The PL spectra results reveal that the annealing temperature plays a key role in the luminescence properties of products. The samples obtained under 650–850?°C exhibit a strong green emission at 546?nm, attributing to the5D4-7F5transition of Tb3+, while the samples produced above 850?°C emit dominating blue lines at 381 and 415?nm, corresponding to the5D3-7F6and5D3-7F5transitions, respectively. The XPS results imply that a part of doping Tb3+ions may be oxidized to Tb4+on the high-temperature thermal treatment process, which could be the reason for the bluish color of Tb-doped YPO4phosphors.
- Yang, Jinyu,Luo, Lin,Chen, Zhuo,Chen, Xueyu,Tang, Xiaoyu
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p. 837 - 842
(2016/08/23)
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- Multifunctional anticancer platform for multimodal imaging and visible light driven photodynamic/photothermal therapy
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As a potential photosensitizer for photodynamic therapy (PDT), pure titanium dioxide has the drawbacks of low tissue penetration and possible damage to skin due to the triggered UV light. To realize near-infrared (NIR) laser-induced multimodal imaging guided therapy, we constructed a multifunctional core-shell structure (TiO2@Y2Ti2O7@YOF:Yb,Tm) by a facile coprecipitation route, followed by an annealing process. Under a single NIR laser irradiation, the highly cytotoxic reactive oxygen species (ROS) required for PDT can be generated due to the energy transfer from YOF:Yb,Tm to the Y2Ti2O7 photocatalyst which is responsive to blue emission (visible light), and the thermal effect can be simultaneously produced due to the nonradiative transition and the recombination of electron-hole pairs. The NIR light induced PDT and photothermal therapy (PTT) can efficiently suppress tumor growth, which was evidenced by both in vitro and in vivo results. Moreover, the rare earth ions in the composite make the material have good up-conversion luminescence (UCL) imaging and CT imaging properties, thus achieving the target of synergistic PDT and PTT therapy under the multimodal imaging guidance.
- Lv, Ruichan,Zhong, Chongna,Li, Rumin,Yang, Piaoping,He, Fei,Gai, Shili,Hou, Zhiyao,Yang, Guixin,Lin, Jun
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p. 1751 - 1763
(2015/03/18)
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- Color-Tunable Luminescence of YNbO4:Ln3+ (Ln3+ = Dy3+ and/or Eu3+) Nanocrystalline Phosphors Prepared by a Sol-Gel Process
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A series of YNbO4:Ln3+ (Ln3+ = Dy3+ and/or Eu3+) phosphors have been synthesized by a Pechini-type sol-gel method. X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy were utilized to characterize the prepared phosphors. The pure phase of YNbO4 was obtained after annealing at 1000 C. The morphologies of the YNbO4:Ln3+ (Ln3+ = Dy3+ and/or Eu3+) phosphors are approximately spherical grains with a diameter of around 40-60 nm. The luminescence properties of the YNbO4:Ln3+ (Ln3+ = Dy3+ and/or Eu3+) phosphors were investigated by photo- and cathodoluminescence methods. Under the excitation of UV light and a low-voltage electron beam, the YNbO4:Ln3+ (Ln3+ = Dy3+ and/or Eu3+) phosphors obtained show characteristic blue wide-band emission from the NbO4 group, whitish light emission from Dy3+, and red emission from Eu3+. Energy is transferred from the YNbO4 host lattice to the Dy3+ and Eu3+ ions. Single-phase white-light-emision was observed in YNbO4:Dy3+ phosphors under the excitation of UV light and a low-voltage electron beam. The color rendering index of the YNbO4:Dy3+ phosphor can be further improved by co-doping YNbO4:Dy3+ with the Eu3+ ion. The emission color of the YNbO4:Dy3+,Eu3+ phosphors can be simply tuned by changing the relative ratio of the Dy3+/Eu3+ ions. The prepared YNbO4:Dy3+ and YNbO4:Dy3+,Eu3+ phosphors have potential applications in UV white-light-emitting diodes and other optoelectronics display devices.
- Lü, Ying,Chen, Chen,Li, Shuailong,Liu, Xiaoming,Yan, Liushui,Dai, Yuhua,Zhang, Aiqin,Xie, Yu,Tang, Xinghua
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p. 5262 - 5271
(2015/11/16)
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- Spectroscopic and structural properties of Na3RE(PO4)2:Yb orthophosphates synthesised by hydrothermal method (RE = Y, Gd)
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Na3RE(PO4)2 orthophosphates, where RE = Y and Gd, doped with Yb3+ ions were synthesised by hydrothermal method and characterised by X-ray diffraction, microscopic, IR and Raman techniques. The emission, excitation spectra were recorded at room temperature and fluorescence decay time was determined. As-synthesised samples crystallise in a trigonal modification and during calcination at 500 °C they transform to a monoclinic or orthorhombic symmetry (for yttrium and gadolinium compounds, respectively). Finally, the samples calcined at 700 °C do not reveal the trigonal symmetry. The morphology of particles for all samples is similar and resembles rice grains. All the obtained for the studied orthophosphates data were compared to those previously reported for the same compounds synthesised by Pechini method.
- Godlewska,Matraszek,Macalik,Hermanowicz,Ptak,Tomaszewski,Hanuza,Szczygie?
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p. 199 - 207
(2015/01/30)
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- Single flexible janus nanobelts to realize tunable and enhanced simultaneous photoluminescent, electrical, and magnetic trifunctionality
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Y2O3:Eu3+ nanoparticles (NPs), polyaniline (PANI), and Fe3O4 NPs are incorporated into polymethyl methacrylate (PMMA) and electrospun into [Y2O3:Eu3+/PMMA]//[PANI/Fe3O4/PMMA] Janus nanobelts with Y2O3:Eu3+/PMMA as one half side and PANI/Fe3O4/PMMA as the other. The morphology and properties of the final products are investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy (OM), energy-dispersive spectrometry (EDS), Hall effect measurements, fluorescence spectroscopy, vibrating sample magnetometry (VSM), and UV/Vis spectroscopy. The results reveal that the [Y2O3:Eu3+/PMMA]//[PANI/Fe3O4/PMMA] trifunctional Janus nanobelts possess excellent electrical conductivity, magnetism, and fluorescence owing to their special nanostructure. Fluorescence emission peaks of Eu3+ are observed in the Janus nanobelts. The electrical conductivity reaches the order of 10-4 S cm-1. The luminescent intensity, electrical conductivity, and saturation magnetization of the Janus nanobelts can be tuned by adjusting the respective amounts of Y2O3:Eu3+ NPs, PANI, and Fe3O4 NPs. The flexible luminescent-electrical-magnetic trifunctional Janus nanobelts have many potential applications. More importantly, this design concept and construct technology is of universal significance for the fabrication of other multifunctional nanostructures. Multifunctional nanostructures: A novel nanostructure of a Janus nanobelt has been fabricated through a simple electrospinning process using a parallel spinneret. Compared with composite nanobelts, these Janus nanobelts possess higher fluorescent intensity, saturation magnetization, and conductivity owing to the isolation of Y2O3:Eu3+ nanoparticles from polyaniline and Fe3O4 nanoparticles (see figure).
- Yin, Duanduan,Ma, Qianli,Dong, Xiangting,Lv, Nan,Wang, Jinxian,Yu, Wensheng,Liu, Guixia
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p. 568 - 575
(2015/03/14)
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- Hollow structured Y2O3:Yb/Er-CuxS nanospheres with controllable size for simultaneous chemo/photothermal therapy and bioimaging
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To integrate photothermal therapy (PTT) with chemotherapy for improved antitumor efficiency, we designed a novel multifunctional composite by attaching CuxS nanoparticles onto the surface of Y2O3:Yb/Er hollow spheres through a combined coprecipitation and subsequent hydrothermal route. By altering the initial pH values for the synthesis of precursors, the size and structure properties of the final composites can controllably be tuned. The conjugated folic acid (FA) makes the composite recognize the targeted cancer cells and the attached CuxS nanoparticles endow the composite with photothermal function. It is found that the release of doxorubicin (DOX) from the functional carrier could be triggered by both pH value and near-infrared (NIR) radiation. In particular, both PTT and chemotherapy can be simultaneously driven by 980 nm laser irradiation. The synergistic therapeutic effect based on PTT and chemotherapy can lead to low in vitro viability of 12.9% and highly strong inhibition of animal H22 tumor in vivo, which is superior to any individual therapy. Moreover, the composite exhibits the clear in vivo red up-conversion luminescence (UCL). This multifunctional nanocarrier can be applicable as bioimaging agent and effective antitumor agent for the synergistic interaction between PTT and the enhanced chemotherapy.
- Lv, Ruichan,Yang, Piaoping,He, Fei,Gai, Shili,Yang, Guixin,Lin, Jun
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p. 483 - 496
(2015/02/05)
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- The role of reaction conditions in the polymorphic control of Eu3+ doped YInO3: Structure and size sensitive luminescence
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With the aim of exploring the effect of particle size and different polymorphic structures on the luminescence behaviour of Eu3+ ions, all in a single compound, the YInO3:Eu3+ system was synthesized. Metastable C-type modification could be obtained in YInO3 nanopowders synthesized by gel combustion. The broadening in Raman modes has been related to both the particle size and the strain in the metastable C-type modification. The hexagonal polymorph of YInO3, with a layered structure, quite unlike the C-type modification, could be obtained by heating nanopowders to 1175°C. Such a change in the structure, leading to different site symmetries for Eu3+ ions exhibited a tremendous bearing on its luminescence behaviour. Detailed steady state and time resolved luminescence studies revealed a highly distorted local site symmetry for the Y3+ ion in hexagonal YInO3. The nano C-type YInO3 exhibited greater asymmetry and a shorter lifetime as compared to the bulk C-type YInO3, attributable to more surface defects in the case of the former. The Judd-Ofelt parameters (Ω2 and Ω4) were determined which established a much higher asymmetry in the hexagonal modification. Along with higher lifetime, the hexagonal polymorph also possessed superior quantum yield values. In addition to providing a significant insight into the structure-luminescence correlation in this study, we propose an efficient red phosphor with a high red color purity.
- Shukla,Gupta, Santosh K.,Grover,Natarajan,Tyagi
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p. 10628 - 10635
(2015/06/16)
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- Preparation and photocatalytic activity of Y-doped Bi2O3
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Y3+ doped Bi2O3 photocatalysts with enhanced photocatalytic activity were synthesized via thermal decomposition of molecular precursor at 500 °C and characterized by X-ray powder diffraction (XRD), Brunauer-Emmett-Teller surface area, field emission scanning electron microscopy (FE-SEM), energy dispersive analysis of X-rays (EDX), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), and photoluminescence spectra (PL). The XRD results indicated that the introduction of Y3+ ions can stabilize the phase of Bi2O3. The DRS results indicated that the doping of Y3+ increased the visible light absorption ability of Bi2O3 and red-shifts appeared when compared with pure Bi2O3. Their photocatalytic activities were evaluated through the photocatalytic degradation of methyl orange. The results showed that an appropriate concentration of yttrium dopant can enhance the photocatalytic performance of Bi2O3 due to the strong visible light absorption and the efficient inhibition of the recombination of photogenerated electron-hole pairs. The active species trapping experiments indicated ·O2- is the main active species in the photocatalytic reaction. Recycling experiments demonstrated that Y-doped Bi2O3 has strong photostability and recyclability and it will be a promising photocatalyst for the photodegradation of organic dyes in water.
- Liu, Xuemei,Deng, Hongquan,Yao, Weilong,Jiang, Qiying,Shen, Juan
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p. 135 - 142
(2015/09/01)
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