7789-82-4Relevant academic research and scientific papers
Chemical vapour transport of ternary oxides in the systems Ca/Mo/O and Sr/Mo/O
Steiner, Udo,Reichelt, Werner
, p. 1257 - 1266 (2006)
The chemical vapour transport behaviour of ternary phases in the Ca/Mo/O and Sr/Mo/O systems has been investigated using Cl2 as transport agent in a temperature gradient 1423 to 1323 K. MMoO4 (M= Ca, Sr) migrate in the above-mentioned temperature gradient with rates of 0.1 to 0.2 mg/h. Starting from three phase mixtures crystals of the compounds MMo 5O8 have been grown (migration rates: M = Ca 0.1 mg/h, M = Sr 0.01 mg/h). The observed transport behaviour is compared with predictions given by thermo dynamical model calculations and the influences of source composition and the moisture contents are described in detail.
ELECTRICAL CONDUCTIVITY OF CaMoO4 .
Petrov,Kofstad
, p. 83 - 88 (1979)
The electrical conductivity and ionic transport number of CaMoO//4 has been measured as a function of the partial pressure of oxygen (1-10** minus **1 **8 atm) at 750, 800, and 850 degree C. Two sets of samples were studied: (1) CaMoO//4 annealed at 1100 degree C in the presence of CaO, and (2) CaMoO//4 annealed in MoO//3 vapor at 1100 degree C. Sample 1 is a mixed ionic/electronic conductor while Sample 2 is essentially an electronic conductor. A defect structure model is proposed to explain the results.
Photophysical and photocatalytic properties of Ca1-xBi xvxMo1-xO4 solid solutions
Yao, Weifeng,Ye, Jinhua
, p. 11188 - 11195 (2006)
New solid solutions with the composition of Ca1-xBi xVxMo1-xO4 prepared by a solid-state method were found as novel photocatalysts with enhanced activity for O 2 evolution from aqueous solu
Self-assembly and photoluminescence characterization of CaMo O4: Eu3+, Na+ superstructure via a facile surfactant-free hydrothermal method
Zhou, Yongqin,Liu, Jie,Yang, Xuyong,Yu, Xibin,Wang, Litong
, p. K74-K80 (2011)
The Eu3+, Na+ -codoped CaMo O4 microphosphors were successfully synthesized at low temperature via a facile hydrothermal method in a surfactant-free environment. Scanning electron microscopy, field-emission scanning electron microscope, and transmission electron microscopy images of the CaMo O4 products prepared at 150°C for 6 h revealed three dimensional flake-ball and flake-disk superstructures, composed of densely packed nanoflakes. The formation mechanism of CaMo O4 microstructures was discussed in detail based on the hydrothermal temperature. Meanwhile, other influencing factors on the morphology were also reported. Room-temperature photoluminescence properties of microsized CaMo O4: Eu3+, Na+ phosphors were studied. Its excitation wavelengths ranging from 350 to 530 nm in the ultraviolet and visible regions significantly extend the excitation region of phosphor materials. In addition, the effect of reactional temperature, pH value, and Ca source on the photoluminescence properties was also studied systematically.
Preparation, characterization and photoluminescence of nanocrystalline calcium molybdate
Phuruangrat, Anukorn,Thongtem, Titipun,Thongtem, Somchai
, p. 568 - 572 (2009)
Nanocrystalline calcium molybdate was successfully synthesized from Ca(NO3)2 and Na2MoO4 in ethylene glycol using a microwave radiation method. Body-centered tetragonal structured calcium molybdate with narrow n
Structural evolution induced by substitution of designated molybdate sites (MoO4?2) with different anionic groups (BO3?3, PO4?3 and SO4?2) in CaMoO4:Sm3+ phosphors-A study on color tunable luminescent properties
Balakrishna,Swart,Ramaraghavulu,Bedyal,Kroon,Ntwaeaborwa
, p. 224 - 237 (2017)
A series of novel red emitting CaMoO4:Sm3+ (1.0 mol %) phosphors substituted with different anionic groups (BO3?3, PO4?3 and SO4?2) were prepared using a high temperature solid state reaction method. The effects of anionic substitution on the crystalline structure and photoluminescence (PL) properties of the CaMoO4:Sm3+, CaMoO4-BO3:Sm3+, CaMoO4-PO4:Sm3+and CaMoO4-SO4:Sm3+ phosphors were investigated. The structure, particle morphology, chemical composition, vibration modes, and PL properties of the phosphors were investigated by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrometry (FT-IR) and PL spectroscopy, respectively. The XRD patterns indicated that the crystalline structures of all the samples were consistent with the standard scheelite structure of CaMoO4. The structural parameters of the pure phase of CaMoO4:Sm3+ phosphor were obtained from the Rietveld analysis. Red PL attributed to the 4G5/2 → 6H9/2 transition of Sm3+ was observed at 646 nm when the CaMoO4:Sm3+ samples were excited by 404 nm using a monochromatized Xenon lamp. Furthermore, orange-red color tunable emission has been achieved by substitution of different anionic groups (BO3?3, PO4?3 and SO4?2) into the CaMoO4:Sm3+ phosphors. Among all the studied phosphors, the CaMoO4-SO4:Sm3+ phosphor showed the strongest PL emission compared to all other phosphors suggesting that it is a promising potential candidate for red emission in the near UV excited white LED applications.
Influence of SO42? anionic group substitution on the enhanced photoluminescence behaviour of red emitting CaMoO4:Eu3+ phosphor
Balakrishna, A.,Letswalo, M. L. A.,Ntwaeaborwa, O. M.,Reddy, L.,Swart, H. C.
, (2021)
CaMoO4:xEu3+(x = 0.5, 1.0, 1.5, 2.0, and 2.5) powder phosphors incorporating SO42? anions were synthesized at high temperature using the solid-state reaction technique. The structural, morphological and optical properties of these phosphors were analysed using X-ray diffraction (XRD), field emission scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and optical spectroscopy. The XRD results indicate that the incorporation of SO42? anions and Eu3+ dopant ions did not affect the crystal structure of the CaMoO4, but largely influenced the luminescence properties of the CaMoO4–SO4:Eu3+ phosphors.The optical properties of our materials were examined using the UV–vis absorption spectroscopy. The absorption edges of the phosphors with different concentrations of Eu3+ were less than the band gap energy of the CaMoO4 and their values ranged from 3.30 to 4.75 eV. The intensity of the red photoluminescence (PL) from CaMoO4:Eu3+ phosphors was enhanced considerably upon incorporation of SO42? anions, suggesting that SO42? acted to capture primary excitation energy and transfer it non-radiatively to Eu3+ ions. In addition, the incorporation of SO42? ions also improved the fluorescence decay life-time values of the CaMoO4:xEu3+ phosphors significantly. Tunable emission was observed when the Eu3+ concentration was varied. Our PL results indicated that the CaMoO4–SO4:Eu3+ phosphor exhibited the highest red emission intensity compared to CaMoO4: Eu3+ phosphors, suggesting that CaMoO4–SO4:Eu3+ could be a promising red component material for potential application in white light-emitting diode devices.
Lanthanide ions-doped calcium molybdate pie-like microstructures: Synthesis, structure characterization, and luminescent properties
Han, Yuanyuan,Wang, Liyong,Wang, Dan,Liang, Danyang,Wang, Shiqi,Lu, Guoxin,Di, Zhiyu,Jia, Guang
, p. 3018 - 3023 (2017)
Lanthanide ions doped CaMoO4with pie-like microstructures were synthesized by a hydrothermal method using phenol-formaldehyde resin (PF) as an inducer. The results of powder X-ray diffraction showed a tetragonal phase of both undoped and Ln3+-doped CaMoO4. The microscopical characterization technology revealed the formation process of the pie-like microparticles. As a morphology inducer, the PF molecules played an important role in the formation of phase structure. The as-obtained materials were characterized using different spectroscopic techniques including FT-IR, Raman spectrum, and PL. The emission color can be easily turned by adjusting the relative doping concentrations of lanthanide ions.
Photoluminescent properties of phosphors in the system Ca xCd1-xMoO4:Eu3+, Li+
Wang, Jiaguo,Jing, Xiping,Yan, Chunhua,Lin, Jianhua,Liao, Fuhui
, p. G534-G536 (2005)
The luminescent properties of the new red phosphors in the solid solution system CaxCd1-xMoO4:Eu3+, Li + are reported. Their dominating emission peaks are at 615 nm, which satisfies color purity. Under the excitation of ～ 320 nm UV light, some selected samples have luminescent intensity 30% higher than that of the commercial red phosphor Y2O2S:Eu3+. Therefore, it is a promising material for N2 plasma display application.
Broadly tunable emission from CaMoO4:Bi phosphor based on locally modifying the microenvironment around Bi3+ Ions
Kang, Fengwen,Peng, Mingying,Xu, Shanhui,Ma, Zhijun,Dong, Guoping,Qiu, Jianrong
, p. 1373 - 1380 (2014)
The trivalent green element of bismuth, when doped into different compounds, can produce multiple emissions in ultraviolet, blue, green or even yellow spectral regimes. The emission adjustability comes from the susceptibility of bismuth naked 6s electrons to the crystal field particularly surrounding Bi3+. However, this has never been observed in a single compound. In this work, we report that broadly tunable bismuth emission indeed occurs even within the same host (CaMoO4) when the local microenvironment around Bi3+ is modified by intentional introduction of alkali ions. As the radius of the selected alkali ion decreases, the emission regularly blue-shifts from 586 to 554 nm, and its intensity is enhanced greatly. For instance, the integrated intensity for the Li+ and Bi3+ codoped sample is 4.46 times stronger than the Bi3+ single-doped sample upon excitation at 300 nm. Low-temperature photoluminescence spectra surprisingly reveal that energy transfer can partially take place from the MoO42- group to Bi3+ at lower temperature when excited into the charge transfer state of the MoO42- group, however, this does not occur at higher temperature. The mechanism needs further study. Dynamic luminescence analysis between 10 and 300 K implies a population dependence of the excited states 3P0 and 3P1 on temperature that is responsible for the evolution of the Bi3+ emission lifetime with temperature. Broadly tunable bismuth emission is observed in the host CaMoO4 when the local microenvironment around Bi3+ is modified by alkali ions. Energy transfer can take place from the MoO42- group to Bi 3+ at lower temperature but not at higher temperature. The dependence of the excited states 3P0 and 3P1 on temperature is responsible for the evolution of the Bi3+ emission lifetime with temperature.
