- Photoluminescence studies on rare earth titanates prepared by self-propagating high temperature synthesis method
-
The laser-induced luminescence studies of the rare earth titanates (R2Ti2O7) (R = La, Nd and Gd) using 355 nm radiation from an Nd:YAG laser are presented. These samples with submicron or nanometer size are prepared by the
- Joseph, Lyjo K.,Dayas,Damodar, Soniya,Krishnan, Bindu,Krishnankutty,Nampoori,Radhakrishnan
-
-
Read Online
- Rare earth tungsten bronzes: A new method of synthesis. Perspectives for their application as inert matrices for transmutation of long-life actinide elements
-
A new method of synthesis of oxide tungsten bronzes containing lanthanide (Ln) Nd and Eu, based on thermal degradation of polyoxotungstate compounds, is proposed. The simplicity of the method allows to consider this class of compounds with chemical formula, LnxWO3, as potential inert target for incineration or transmutation of minor actinides, Am and Cm, in neutron reactors. Nd and Eu were used as analogues of transplutonium elements. Powder X-ray diffraction patterns of compounds synthesized reveal a cubic perovskite structure. The lanthanide content in bronzes was determined by optical spectroscopy analysis. The experimental density of the pressed bronze samples was estimated at 6.58 g cm-3, i.e., 89% of the crystallographic value. The thermal stability of the bronzes synthesized was checked up to 900°C in an inert atmosphere. Leaching tests were performed for europium bronzes in nitric acid solutions using luminescence technique.
- Bessonov,Fedosseev,Krupa,Shirokova,Budantseva
-
-
Read Online
- Preparation of nanopowdered M1-x R x F2+x (M = Ca, Sr, Ba; R = Ce, Nd, Er, Yb) solid solutions
-
The synthesis procedure has been worked out, and nanopowders of fluoride solid solutions (ss) Ca1-x R x F2+x (R = Er, Yb), Sr1-x Nd x F2+x , and Ba1-x Ce x F2+x/
- Kuznetsov,Yarotskaya,Fedorov,Voronov,Lavrishchev,Basiev,Osiko
-
-
Read Online
- Spectroscopic properties of Nd3+ in MgAl2O 4 spinel nanocrystals
-
Nd3+ doped MgAl2O4 spinel nanocrystals have been prepared by the sol-gel method. Their size decreases from 12 to 7 nm with increasing Nd3+ concentration from 0.1 to 5%, respectively. Some crystal field component
- Dereń,Maleszka-Bagińska,G?uchowski,Ma?ecka
-
-
Read Online
- Moderate pressure synthesis of rare earth nickelate with metal-insulator transition using polymeric precursors
-
Rare earth nickelates exhibit a reversible metal-semiconductor phase transition that is, in the infrared range, responsible for a thermo-optical contrast. The state of the art synthesis of these compounds usually requires high oxygen pressure to stabilize Ni in the oxidation state 3+. In this work, using polymeric precursor associated with moderate pressure annealing, we show that it is possible to obtain fully oxidized rare earth nickelate with metal-insulator transition. Using thermogravimetric analysis, X-ray diffraction and transmission electronic microscopy we compare different samples synthesized at different oxygen pressures and demonstrate their structural similarity. Thermo-optical properties were measured, in the infrared range, using reflectance measurements and confirmed the metal-insulator transition at 60 °C in both samples.TEM observations lead to the conclusion that the structure commonly obtained at 175 bar is perfectly observed in the 20 bar sample without major structural defects. The two samples exhibit a thermochromic behavior and thermo-optical properties of the two samples are equivalent.
- Napierala,Lepoittevin,Edely,Sauques,Giovanelli,Laffez,VanTedeloo
-
-
Read Online
- Synergistic extraction and solution structures of ternary complexes of lanthanoids with 2-thenoyltrifluoroacetone and linear poly(oxyethylene) in 1,2-dichloroethane
-
Synergistic extraction of thenoyltrifluoroacetone (tta) complexes of 14 trivalent lanthanoids (Ln3+) into 1,2-dichloroethane with linear poly(oxyethylene) compounds (POE) was investigated at 25.0°C, where the linear POE [HO-(CH2CH2O-)nR] are monodispersed DEOn (R = C12H25; n = 4, 6, and 8) and polydispersed TX-100 (R = octyl-phenyl; nave = 9.6). Equilibrium studies showed a 1:1 adduct complex with POE compound, Ln(tta)3 · (POE), formed in the organic phase. The adduct formation constant, βadd, increased as the ionic radius of lanthanoid increased for any kind of POE. The very high stability of the 18-crown-6 adducts is explained by the incorporation of Ln3+ ion into the cavity of the crown ether. Adduct formation constants of the POE having short ethylene oxide (EO) chain, such as DE04 and 12-crown-4, were fairly small; thus, it was estimated that those coordinate to the metal ion as a bidentate or tridentate ligand. Relatively large values of βadd of long chain POE (n ≥ 6) indicate the indirect outer-sphere interaction of the uncoordinated residual EO units with the metal ion. Adduct formation with linear POEs significantly reduced the difference in extraction constants among the lanthanoid ions. Therefore, this synergistic extraction system is advantageous for the separation of lanthanoid ions as a group from other metal ions.
- Gagabe, Gene Frederick,Satoh, Yuta,Satoh, Keiichi,Sawada, Kiyoshi
-
-
Read Online
- The coupled TG-MS investigations of lanthanide(III) nitrate complexes with hexamethylenetetramine
-
New transition metal compounds of the general formula Ln(NO 3)3·2[N4(CH2) 6]·nH2O, where Ln = La, Nd, Sm, Gd, Tb, Dy, Er, Lu, and n = 7-12, were obtained. The compounds and the gases evolve
- Zalewicz,Trzesowska
-
-
Read Online
- Complexation thermodynamics of rare earth (III) with crown ethers. 31.Calorimetric titration of light lanthanoid (III) nitrates with dibenzo-18-crown-6 in acetonitrile
-
Calorimetric titrations have been performed in anhydrous acetonitrile at 25°C to give the complex stability constants (Ks) and the thermodynamic quantities for the complexation of light lanthanoid (III) nitrates (La-Gd) with 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclooctadeca-2,11-diene (dibenzo-18-crown-6) (2). Data analyses, assuming 1 : 1 stoichiometry were successfully applied to all the light lanthanoid-crown ether combinations employed. Using the present and reported data, the complexation behaviors of (2) and 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) (1) are compared from the thermodynamic point of view. The rigid structure of (2), as compared with (1), gave the higher Ks for Nd3+ and Sm3+ among the light lanthanoid nitrates. The complex stability sequence as a function of reciprocal ionic diameter of lanthanoid showed a monotonically declining pattern for (1) except for a jump at Ce3+, and a characteristic peak profile at Nd3+ and Sm3+ for (2). Thermodynamically, the complexation of light lanthanoid nitrates with 18-crown-6 is mainly enthalpy-driven in acetonitrile, but the complexation with (2) is chiefly entropy-driven.
- Liu, Yu,Han, Baohang,Zhang, Zhihui,Guo, Jihui,Chen, Yunti
-
-
Read Online
- Effect of rare earth substitution on magnetic and structural properties of Co1-xREx Fe2O4 (RE: Nd, Eu) nanoparticles prepared via EDTA/EG assisted sol-gel synthesis
-
Four groups of the series of rare earth (RE) substituted cobalt ferrite Co1-x REx Fe2 O4; x = 0-0.2 in steps of 0.05 and RE is Nd and Eu were prepared using the sol-gel method at annealing temperatures 550° C. The materials were characterized by powder X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM) and Fourier Transform Infrared spectroscopy (FTIR). The phase identification of the materials by XRD reveals the single-phase nature of the materials. The crystallite sizes of the materials were varied by altering the substitution content within the range of a minimum of 11 nm-31 nm. The magnetic parameters have been studied by using vibrating sample magnetometer (VSM). The saturation magnetization of the ferrite materials at room temperature decreases with the reduction of size. This has been attributed to increased surface to volume ratio and spin canting phenomena. The substituted rare-earth ions inhibit the grain growth of the materials in a systematic manner compared with that of the pure cobalt ferrite materials. There is an improvement in coercivities of the rare earth substituted cobalt ferrite especially for 5% Neodymium substituted cobalt ferrite with approximately 2 kOe coercive field. This is attributed to the contribution from the single ion anisotropy of the rare-earth ions present in the crystal lattice and the effects of a change in magnetic structures on the surface of the nanoparticles.
- Avazpour,Shokrollahi,Toroghinejad,Zandi Khajeh
-
-
Read Online
- Synthesis of Ba4R3F17 (R stands for rare-earth elements) powders and transparent compacts on their base
-
Single-phase samples of Ba4R3F17 ? nH2O (R = La, Ce, Pr, Nd, Eu, Gd, Y, Er, or Yb; n = 2.5-3.2) were prepared by coprecipitation from nitrate solutions using hydrofluoric acid. The phases crystallize in a fluorite-type face-centered cubic lattice. The dried precipitates are transparent. Scanning electron and atomic-force microscopy and X-ray diffraction line broadening show a hierarchic structure in the samples: primary nanoparticles join into agglomerates with characteristic sizes of about 150-200 nm, these agglomerates being self-packed into parallel layers with a thickness on the order of 500 nm.
- Kuznetsov,Fedorov,Voronov,Samarina,Ermakov,Osiko
-
-
Read Online
- Hydrothermal synthesis, structural, Raman, and luminescence studies of Am[M(CN)2]3·3H2O and Nd[M(CN)2]3·3H2O (M=Ag, Au): Bimetallic coordination polymers containing both trans-plutonium and transition metal elements
-
The polymeric compounds consisting of the man-made element, americium, and gold and silver dicyanides were prepared under mild hydrothermal conditions at 120 °C. It was found that the americium ion and the transition metal ions are interconnected through cyanide bridging in the compounds. Given the similarities in the radii of americium and neodymium, crystals of the latter were also characterized for comparison purposes. The four compounds are isostructural and crystallize in the hexagonal space group, P63/mcm, with only slight differences in their unit cell parameters. Crystallographic data (MoKα, λ=0.71073 A): Am[Ag(CN)2]3·3H2O (1), a=6.7205(10) A, c=18.577(3) A, V=726.64(19), Z=2; Am[Au(CN)2]3·3H2O (2), a=6.666(2) A, c=18.342(3) A, V=705.9(4), Z=2; Nd[Ag(CN)2]3·3H2O (3), a=6.7042(4) A, c=18.6199(14) A, V=724.77(8), Z=2; and Nd[Au(CN)2]3·3H2O (4), a=6.6573(13) A, c=18.431(4) A, V=707.2(2), Z=2. The coordination around the Am and/or Nd consists of six N-bound CN- groups resulting in a trigonal prismatic arrangement. Three capping oxygen atoms of coordinated water molecules complete the tricapped trigonal prismatic coordination environment, providing a total coordination number of nine for the f-elements. Raman spectroscopy, which compliments the structural analyses, reveals that the four compounds display strong signals in the νCN stretching region. When compared with KAg(CN)2 or KAu(CN)2, the νCN stretching frequencies for these compounds blue-shift due to bridging of the dicyanometallate ions with the f-element ions. There is subsequent reduction in electron density at the cyanide center. Compared with the silver systems, the νCN frequency appears at higher energy in the gold dicyanide complexes. This shift is consistent with the structural data where the carbon-nitrogen bond distance is found to be shorter in the gold dicyanides.
- Assefa, Zerihun,Kalachnikova, Katrina,Haire, Richard G.,Sykora, Richard E.
-
-
Read Online
- Thermodynamic characterization of rare earth salts of strong polyacid copolymers
-
Stoichiometric La3+, Ce3+, and Nd3+ salts of poly[(vinyl alcohol)-co-(vinyl sulfate)] (PVAS) copolymer polyacids have been studied in aqueous solution without added salt. All LnPVAS salts were entirely watersoluble in the composition and concentration range investigated. Ratios of the vinyl sulfate and vinyl alcohol units in the copolymers were between 1:5 and 1:107, leading to structural charge densities both above and under the critical value needed for counterion condensation of trivalent counterions. Solvent activity, a1, has been measured by the gel deswelling method in the concentration range of 5 × 10-4 to 1 × 10-1 mol of counterion/kg of water (0.2-9 w/w% of the poly electrolyte). Results are unusually high for polyelectrolytes (-2 × 10-6 > In a 1 > -3 × 10-4), and they are comparable with values determined in solutions of uncharged polymers. Nevertheless, the different copolymers can be clearly distinguished; the water activity is lowered in the order of the vinyl sulfate content of the polyelectrolytes, except for the one above the critical charge density. No observable difference was caused in the thermodynamic properties by the different lanthanide counterions. Reduced osmotic pressure curves and Flory-Huggins pair interaction parameters have been calculated; both of them were used to estimate degrees of dissociation at zero as well as at finite concentrations. Degrees of dissociation are decreasing with increasing concentration or vinyl sulfate content of the copolymer. They take values between 8-36% at zero polymer concentration and they reach zero value simultaneously at ～1 × 10-3 mol of polymer chains/kg of water. The average number of released counterions per polymer chain (DP n = 1005) approaches to a limit of about 4.4 with increasing vinyl sulfate content. This corresponds to average charge distances of b ≥ 19 nm and charge density parameters of ξ ≤ 0.037. The latter is, however, a very low value and indicates a 1/9 contraction compared to the rod-like assumption.
- Horvath, Judit,Nagy, Miklos
-
-
Read Online
- Lanthanide complexes with diethyl(2-oxopropyl) phosphonate and diethyl(2-oxo-2-phenylethyl) phosphonate ligands
-
Ln3+ complexes with the phosphonate ligands: diethyl(2-oxopropyl) phosphonate [CH3C(O)CH2P(O)(OC2H5)2] (OPP) and diethyl (2-oxo-2-phenylethyl) phosphonate [C6H5C(O)CH2P(O)(OC2H5)2] (DEPP) were synthesized and characterized. Complexation studies and spectral characterizations are performed. Based on the Nd3+ absorption spectra, using computer-assisted target factor analysis, the stability constants of Nd-OPP complexes in solution were determined to be log β11 = 2.8 ± 0.4 and log β12 = 5.0 ± 0.7. Luminescence intensities, lifetimes, τ, and quantum yields, Φ, of the Eu3+ and Tb3+ ions in the complexes were measured. The most intense luminescence was observed in the case of the Tb/DEPP system. Emission enhancements were observed for Tb3+ and Eu3+ complexes in acetonitrile solutions, which occurred as a result of sensitized luminescence. These observed luminescence intensities were over two orders of magnitude larger than those for the uncomplexed Ln(III) ions. The complexes of Ln/L/NO3, obtained in oil forms from ethanol at room temperature, were characterized by elemental analysis, IR spectroscopy, and luminescence lifetime measurements. The composition of the complexes studied is suggested to be LnL2(NO3)3, with monodentate coordination by the phosphoryl group.
- Hnatejko,Lis,Pawlicki,Meinrath
-
-
Read Online
- Thermal, spectral and magnetic behaviour of 4-chloro-2-methoxybenzoates of light lanthanides(III)
-
4-Chloro-2-methoxybenzoates of light lanthanides(III) were obtained as mono-, di-or trihydrates with metal to ligand ratio of 1:3 and general formula Ln(C8H6ClO3)3?nH2O, where n=1 for Ln=Ce, Pr, n=2 for Ln=Nd, Sm, Eu, Gd and n=3 for Ln=La. The complexes were characterized by elemental analysis, IR spectra, thermogravimetric studies, X-ray diffraction and magnetic measurements. The carboxylate group appears to be a symmetrical bidentate, chelating ligand. All complexes seem polycrystalline compounds. Their thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which next are decomposed to the oxides of the respective metals. The solubilities of light lanthanide(III) 4-chloro-2-methoxybenzoates in water at 293 K are of the order of 10-5 mol dm-3. The magnetic moments were determined over the range of 77-300 K. They obey the Curie-Weiss law. The values of μeff calculated for all compounds are close to those obtained for Ln3+ by Hund and Van Vleck. The results indicate that there is no influence of the ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature.
- Ferenc, Wieslawa,Cristovao,Sarzynski,Wojciechowska, Maria
-
-
Read Online
- Preparation and thermal reactivity of some rare earth and uranyl hydrazinesulfinates and sulfite hydrazinates
-
Hydrazinesulfinate and sulfite hydrazinate derivatives of rare earth elements of composition Ln(N2H3SOO)3(H 2O) and Ln2(SO3)3(N 2H4)x(H2O)y, respectively, where Ln=La, Ce, Pr, Nd and Sm, have been prepared and characterized by chemical analysis and infrared spectra. The uranyl complexes of the composition UO2(N2H3SOO)2, UO2(N2H3SOO)2(N2H 4) and UO2SO3(N2H 4)(H2O) have also been prepared under different reaction conditions and studied by different physicochemical techniques. Thermal properties of all these complexes have been studied by thermogravimetry, and differential scanning calorimetry. The hydrazinesulfinate derivatives of rare earth elements undergo thermal decomposition in multisteps to give the respective metal sulfate as the residue. The other series of complexes, viz., rare earth sulfite hydrazinates gave a mixture of metal sulfate and metal oxide as the end products. However, all the uranyl complexes undergo decomposition in air to give UO2SO3 as the final product.
- Sivasankar,Sharmila,Saratha,Govindarajan
-
-
Read Online
- Lanthanide-Nitrate Interaction in Anhydrous Acetonitrile and Coordination Numbers of the Lanthanide Ions: FT-IR Study
-
The interaction between lanthanide ions LnIII (Ln = La, Nd, Sm-Dy, Er, Yb) and nitrate ions is investigated by FT-IR spectroscopy in dilute anhydrous MeCN solution.The work is performed for ratios R = t/III>f ranging from 0 to 8 and for solutions generally 0.05 M in LnIII, prepared from anhydrous lanthanide perchlorates Ln(ClO4)3.When nitrate is progressively added to the Ln(ClO4)3 solutions, the formation of n>(3-n)+ species is clearly evidenced by the FT-IR spectra.All the NO3(1-) ions are coordinated and bidentate.A quantitative study was performed using the v1 and v6 vibrational modes for coordinated NO3(1-) ions.The average coordination numbers estimated for Nd, Eu, Tb, and Er in solutions of trinitrates are 9.0, 9.1, 8.3, and 8.2, respectively ( +/- 0.3 unit).In presence of an excess NO3(1-), these numbers become 9.8, 10.2, 10.0, 9.8, 9.9, and 9.9 (+/- 0.3 unit) for La, Nd, Eu, Tb, Er, and Yb, respectively.No hexanitrato species forms under the experimental conditions used (R up to 8).The structural aspect of the various nitrato species is also investigated.In the pentanitrato species, all the ligands appear to be equivalent, while large inequivalences are observed for Ln(NO3)3 solutions.Since for the latter most of the absorption bands assigned to nitrate vibrations contain several components, a curve-fitting procedure has been used for decomposing the v2, v4, and v6 vibrations.There is a considerable difference between LnIII ions, the nitrate inequivalences being larger in the middle of the series.
- Buenzli, Jean-Claude G.,Milicic-Tang, Anita,Mabillard, Catherine
-
-
Read Online
- Synthesis and characterization of nanocrystalline Nd3+-doped gadolinium scandium aluminum garnet powders by a gel-combustion method
-
Nd3+-doped gadolinium scandium aluminum garnet (Nd:GSAG) precursor was synthesized by a gel combustion method using metal nitrates and citric acid as raw materials. The structure and morphology of the precursor and the sintered powders were studied by means of X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). The results showed that the precursor transformed into pure GSAG polycrystalline phase at about 800 °C, and the powders sintered at 800-1000 °C were well-dispersed with average particle sizes in the range of 30-80 nm. Optical properties of Nd:GSAG nano-powders were characterized by using photoluminescence spectroscopy. The highest photoluminescence intensity was achieved for the powder sintered at 900 °C.
- Su, Jing,Miao, Ju-Hong,Xu, Lin-Hua,Ji, Yu-Qing,Wang, Chu-Qin
-
-
Read Online
- Synthesis and characterization of neodymium oxide nanoparticles
-
The nanometric precursors of neodymium oxide of various morphology from fibrous to well-dispersed spheroidal were prepared via a solvothermal reaction routes. The precursors and their thermal evolution to neodymium oxide phase were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It was found that the reaction parameters, kind of solvent as well as neodymium salt used played a key role for the product formation of desired morphology and structure. Similarly, kind of neodymium oxide precursor determined the morphology and the crystal structure (haxagonal or cubic) of the final oxide. The potential application of Nd2O3 precursors prepared by solvothermal method as convenient material for preparation of homogeneous thin coatings on planar substrates is shown.
- Zawadzki, Miros?aw,K?piński, Leszek
-
-
Read Online
- Molecular design of crown ethers. 13. Complexation thermodynamics of light lanthanoid nitrates with aza-16-crown-5 lariat in acetonitrile: Enhanced selectivity for Nd3+
-
Calorimetric titrations have been performed in anhydrous acetonitrile at 25°C to give the complex stability constants (Ks) and the thermodynamic parameters for the stoichiometric 1:1 complexation of light lanthanoid-(III) nitrates (La-Gd) with N-methoxyethylaza-4,7,11,14-tetraoxacyclohexadecane (aza-16-crown-5 lariat) (1). Using the present and reported data, the complexation behavior of C- and N-pivot lariats with 16-crown-5 skeletons is discussed comparatively and globally from the thermodynamic point of view. Possessing structural flexibility as compared with lariat ether 15-(2,5-dioxahexyl)-15-methyl-1,4,7,10,13-pentaoxacyclohexadecane (16-crown-5 lariat) (2), aza-16-crown-5 lariat gave the highest Ks for Nd3+ among the light lanthanoid nitrates. The complex stability sequence as a function of reciprocal ionic diameter of lanthanoid showed a characteristic peak profile at Nd3+ for 1, the relative cation selectivity for Nd3+ over the neighboring Pr3+ and Sm3+ amounted to 9. Thermodynamically, the complexation of light lanthanoid nitrates with the lariat ethers is mainly enthalpy-driven in acetonitrile, but the cation selectivity is entropy-governed. The high cation selectivity of aza-16-crown lariat (1) is attributed to the entropic loss that is minimized only when a strict size match is materialized between the ionic diameter of the lanthanoids and the relatively flexible three-dimensional cavity induced upon lariat ligation. Therefore, the three-dimensional induced fit plays an important role in the recognition of trivalent lanthanoid ions by lariat ethers with structural flexibility.
- Liu, Yu,Han, Bao-Hang,Li, Yu-Mei,Chen, Rong-Ti,Ouchi, Mikio,Inoue, Yoshihisa
-
-
Read Online
- A New Octadecanuclear Copper(II)-Lanthanide(III) Cluster Complex: Synthesis and Structural Characterization of [Cu12Nd 6(OH)24(betaine)16(NO3) 3(H2O)10](NO3)[PF6] 14·5H2O
-
The new octadecanuclear Cu-Ln complex, [Cu12Nd 6(OH)24(betaine)16(NO3) 3(H2O)10](NO3)[PF6] 14·5H2O, was synthesized, which crystallizes in triclinic P1 space group, a = 18.649(6) A, b = 20.363(7) A, c = 19.865(7) A, α = 116.61(2)°, β = 91.99(2)°, γ = 117.93(2)°, V = 5666(3) A3. Its crystal structure features a [Cu12Nd6(OH)24(betaine) 16(NO3)3(H2O)10] 15+ core of pseudocubic Oh symmetry, with the six Nd ions positioned at the vertices of a regular octahedron and the twelve Cu ions located at the midpoints of the twelve octahedral edges. The Cu-Nd metal framework may be viewed as a cuboctahedron, which is interconnected by twenty-four μ3-OH bridges that are each linked to one Nd ion and two Cu ions. In the centre of metal polyhedron, there is an encapsulated NO 3- anion that exhibits a multi- coordinating mode.
- Yang, Yang-Yi,Huang, Zhong-Qi,He, Feng,Chen, Xiao-Ming,Ng, Seik Weng
-
-
Read Online
- Properties of a novel Ba5Si8O21:Eu2+, Nd3+ phosphor: Bulk and 1D nanostructure with PVP synthesized by sol-gel and electrospinning
-
In this study, a sunlight-activated Ba5Si8O21:Eu2+, Nd3+ (BSEN) persistent luminescent particles were firstly synthesized by sol-gel method, and then combined with polyvinyl pyrrolidone (PVP) to fabricate one-dimensional functional fiber by electrospinning. XRD, photoluminescence, fluorescence microscope, SEM and TEM were used to investigate the crystal structure, the morphology, the luminescent properties and water resistance of BSEN particles and functional fibers. The results show that BSEN owns a monoclinic crystalline and can be effectively and repeatedly excited by both ultraviolet and sunlight. The BSEN particles were water-resistant and uniformly dispersed in the PVP fibers. Both BSEN particles and functional fibers possessed broad excitation spectra from 250?nm to 450?nm with maximum at 341?nm and exhibited a fluorescent and phosphorescent emission band from 365?nm to 650?nm with maximum at around 489?nm with long afterglow up to 240?min. The new functional fiber has potential to be used in flexible coating, textile and optical display.
- Yao, Yuanlin,Zhou, Zhufa,Ye, Feng
-
-
Read Online
- Synthesis of reactive neodymia-doped zirconia powders by the sol-gel technique
-
Zirconia-x mol% neodymia (x = 3, 5 and 8) solid solutions were prepared by the sol-gel technique. The aim of this work is to obtain reactive ceramic powders with high structural homogeneity using a simple method of solid solution synthesis. Powder characterization comprises: thermal analyses to study the decomposition behavior of the precursor; laser scattering to obtain the particle size distribution; scanning electron microscopy to observe shape and size of the agglomerated particles; X-ray diffraction experiments on sintered specimens for phase characterization, and dilatometric experiments to obtain the linear shrinkage of a powder compact.
- Muccillo,Souza,Muccillo
-
-
Read Online
- Isolation, spectroscopic and thermal properties of hydrazinium tris(oxydiacetato)lanthanate(III) hemi(pentahydrate): Crystal structure of the neodymium complex
-
Oil-bath reaction of respective metal nitrate with an aqueous mixture of oxydiacetic acid (H2oda) and hydrazine hydrate led to the formation of crystalline compounds with formula (N2H5)3[Ln(oda)3]·2.5H2O (where Ln?=?La, Ce, Pr, Nd and Sm), which are stable for a week and undergo efflorescence. The resulting complexes were characterized by infrared spectral, thermal (air and nitrogen atmosphere), UV–visible and PXRD studies. From the thermal studies, both in air and nitrogen atmosphere, these compounds show endothermic dehydration below 100?°C to give anhydrous compounds. Next, the anhydrous compounds (in air) undergo endothermic decomposition between 190 and 225?°C to form Ln(Hoda)3 intermediate, which further show exothermic decomposition to yield respective metal oxide as the end residue. But, in nitrogen atmosphere, the same anhydrous compounds exhibit endo-followed by exothermic decompositions to give respective metal as end product. This is observed as a continuous single step of decomposition in TG. The structure of (N2H5)3[Nd(oda)3]·2.5H2O has been determined by single-crystal X-ray analysis. The neodymium atom is coordinated by nine oxygen atoms from three tridentate (O, O, O) oxydiacetate ions with tricapped trigonal prismatic geometry. In addition, both the parent acid and its compounds display strong fluorescent emission due to the ligand, which renders them as fluorescent materials at room temperature.
- Kanchana,Packiaraj,Pushpaveni,Govindarajan
-
-
Read Online
- Synthesis, morphology and spectroscopy of Nd:GSAG nano-powders
-
Nd3+-doped gadolinium scandium aluminum garnet (Nd:GSAG) precursors were obtained from a mixed nitrate solution with precipitant of ammonium hydrogen carbonate. The precursors were sintered at different temperatures and the phase developments in heat treatments were investigated through methods of XRD and IR, showing the precursors transformed to pure-GSAG phase with no intermediate phases appeared at 900 °C. The TEM observation revealed that the powders sintered at 900-1000 °C were well-dispersed with average crystalline sizes of 30-80 nm. Photoluminescence analysis of the Nd:GSAG nano-powders showed that the PL intensities changing significantly with the Nd3+ doping concentration, and the concentration quenching was observed as the Nd3+ concentration reached to 1.5 at.%.
- Su, Jing,Yao, Yijun,Liu, Bin,Xu, Linhua
-
-
Read Online
- Non-centrosymmetric rubidium rare-earth nitrates Rb2IHT(NO 3)54H2O: Crystal growth and optical properties
-
Large single crystals of optical quality of the isomorphic, non-centrosymmetric, monoclinic (space group Cc) compounds Rb 2La(NO3).4H2O and Rb2Ce(NO 3)., ? 4H2O were grown. The determinatio
- Bohaty, Ladislav,Held, Peter,Becker, Petra
-
-
Read Online
- Thermoanalytical and spectroscopic studies on hydrazinium lighter lanthanide complexes of 2-pyrazinecarboxylic acid
-
The new hydrazinium lanthanide metal complexes of 2-pyrazinecarboxylic acid (HpyzCOO) of the formulae (N2H5)2[Ln(pyzCOO) 5] ? 2H2O (1), where Ln = La or Ce and (N 2H5)3/sub
- Premkumar, Thathan,Govindarajan, Subbiah
-
-
Read Online
- Tetrad effect in the distribution constants of the lanthanides in their adsorption on the zeolite a
-
In this study, the changes of the distribution constants Kd of the lanthanide nitrates in the system: zeolite A (solid phase)-sodium nitrate (aqueous phase) were investigated. The convex and concave tetrad effect in the run of the Kd values of the lanthanides was found. The explanation of the tetrad effect through the covalency in Ln-O lanthanide bond (where Ln is lanthanide, O- oxygen) is included. It is evident from the supplementary data of diffusive reflectance spectra of the zeolites and lanthanide oxides in the VIS and infrared region, that the Nd3+ ion forms more covalent complex with the negatively charged oxygen atoms of the zeolite framework than the rest of the lanthanide ions and that La3+, Nd3+, Sm 3+ ions strongly hydrolyze in the zeolite phase, which results in the shift of T-O-T band (asymmetric stretching vibration band of -Si-O-Al-subunits) toward lower wavelengths.
- Majdan, Marek,G?adysz-P?aska, Agnieszka,Pikus, Stanis?aw,Sternik, Dariusz,Maryuk, Oksana,Zieba, Emil,Sadowski, Pawe?
-
-
Read Online
- NIR emission in Ba2SiO4:Eu2+, Nd3+ phosphors with near UV/violet excitation
-
New results on NIR emission in Ba2SiO4:Eu2+, Nd3+ phosphors are reported. Though excitation for Eu2+ emission is in predominantly near UV (nUV) region, that for the Nd3+ emission around 106
- Vyas, Arpita,Joshi,Sahare,Moharil
-
-
Read Online
- Synthesis and Spectral Studies of Piprazine Schiff Base Lanthanide(III) Complexes and their Microbial and Anticancer Activity
-
A novel Schiff base ligand has been synthesized by the condensation reaction of 1-(2-amino ethyl)piprazine with o-vanillin in methanol solution. Using lanthanide(III) metal ions (Ln3+ = La3+, Ce3+, Pr3+, Nd3+, Sm3+ and Gd3+) in methanol, six complexes of
- Geethalakshmi, V.,Nalini, N.,Sabithamala, S. S.,Tamilselvi, D.,Theivarasu, C. T.
-
p. 155 - 161
(2022/01/06)
-
- Generalized synthesis of NaLn(MoO4)2 nano/microcrystals (Ln = La–Lu and Y): The effects of lanthanide contraction, structure, and down-/up-conversion luminescence
-
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
-
-
- HDEHP assisted solvothermal synthesis of monodispersed REPO4 (RE = La-Lu, Y) nanocrystals and their photoluminescence properties
-
Coordination polymer submicrospheres were successfully synthesized using a solvothermal method using organophosphate (HDEHP) and Y(NO3)3 without any additional ligand and surfactant under mild conditions. Upon calcination, the obtained precursor produced stable tetragonal phase (t-)YPO4 submicrospheres. XRD, SEM and HRTEM were used to characterize the precursor and calcined samples. The results showed that t-YPO4 submicrospheres were obtained by the thermal decomposition of the precursor, and there was no other phase transition in the process. FTIR and TG-DTA confirmed that the precursor was a coordination polymer formed by HDEHP and Y3+, and the growth process of the spherical precursor was proposed. Furthermore, various REPO4 (RE = La-Lu, except radioactive Pm) spherical particles and the Eu3+ doped YPO4 phosphor were synthesized under similar conditions. The luminescent properties of the YPO4:Eu phosphor were also studied in detail.
- Yang, Zhen,Yuan, Guangzhen,Duan, Xiannan,Liang, Shuai,Sun, Guoxin
-
p. 4386 - 4393
(2020/03/26)
-
- Step by step designing of sensitive luminescent nanothermometers based on Cr3+,Nd3+ co-doped La3-: XLuxAl5- yGayO12 nanocrystals
-
In this work we present step by step designing of sensitive luminescent thermometers utilizing Cr3+,Nd3+ co-doped La3-xLuxAl5-yGayO12 garnets. In order to achieve this purpose, modification of the local ion environment by the adjustment of the La3+ to Lu3+ and the Al3+ to Ga3+ ion ratios was performed. Additionally, the influence of the Cr3+ and Nd3+ ion concentration on the thermal quenching of Cr3+ luminescence was investigated. All of the abovementioned steps of the host stoichiometry optimization enabled us to obtain a relative sensitivity of luminescent thermometers based on the luminescence intensity ratio of Nd3+(4F5/2 → 4I9/2)/Cr3+(2E → 4A2) electronic transitions as high as S = 1.47% °C-1 at -150 °C and S = 1.23% °C-1 at 260 °C for La2LuGa5O12:1%Cr3+,5%Nd3+ nanocrystals. The presented studies provide the verification how stoichiometry of host material affect the relative sensitivity of transition metal/lanthanide ion based luminescent thermometers, enabling knowledgeable designing of highly sensitive luminescent thermometers.
- Elzbieciak-Piecka,Matuszewska,Marciniak
-
p. 12614 - 12622
(2019/08/21)
-
- Effect of silica coating on luminescence and temperature sensing properties of Nd3+ doped nanoparticles
-
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
-
p. 136 - 143
(2017/11/15)
-
- New rare earth langbeinite phosphosilicates KBaREEZrP2SiO12 (REE: La, Nd, Sm, Eu, Gd, Dy) for lanthanide comprising nuclear waste storage
-
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
-
p. 422 - 429
(2015/11/16)
-
- Ionic conductivity of Nd3+ and Y3+ co-doped ceria solid electrolytes for intermediate temperature solid oxide fuel cells
-
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
-
p. 513 - 519
(2015/11/25)
-
- Eu3+ local site analysis and emission characteristics of novel Nd2Zr2O7:Eu phosphor: Insight into the effect of europium concentration on its photoluminescence properties
-
A new zirconate-based pyrochlore-type red phosphor, Nd2Zr2O7:Eu3+, was synthesized using the gel-combustion method. The un-doped sample showed visible emission due to the presence of oxygen vacancies. On doping with europium ions, it was found that Eu was distributed into both Nd3+ as well as Zr4+ sites based on emission and lifetime spectroscopy with a lifetime value of 3.35 and 1.14 ms, respectively, although the population at the Zr4+ site is more than that at the Nd3+ site. This is also justified by the presence of two stark components in the 5D0-7F0 transition. The presence of host emission in the spectrum of Nd2Zr2O7:Eu3+ indicated incomplete energy transfer process at low levels of europium doping. Moreover, the efficiency of energy transfer increased as the doping percentage increased, and complete host-dopant energy transfer took place at 5.0% Eu3+ doping. Based on time resolved emission spectroscopy (TRES), the emission spectrum of europium into the Nd3+ sites as well as at Zr4+ sites was elucidated. Calculation of the Judd-Ofelt parameter illustrated that at all europium concentration, the local surrounding area lacks inversion symmetry (asymmetric environment) and the exact point group symmetry was found to be C4. The red purity and high quantum efficiency of Nd2Zr2O7:Eu3+ projects it to be a new materials for commercial application in white light emitting diodes.
- Gupta, Santosh K.,Reghukumar,Kadam
-
p. 53614 - 53624
(2016/07/06)
-
- Construction of monomers and chains assembled by 3d/4f metals and 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine
-
A series of transition metal and lanthanide complexes of 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine (HL, 1), namely [M(L)2]·5H2O (M=Ni, 2; Co, 3), [Zn(L) 2]n·0.5nH2O (4) and [Ln(L) 3]n (Ln=Nd, 5; Gd, 6; Er, 7) were hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Isomorphic compounds 2 and 3 are mononuclear molecules with two ligand chelating to the metal centers via tridentate terpyridyl, while compound 4 adopts 1D chain-like structure, in which five-coordinate zinc centers are surrounded by three ligands. Compounds 5-7 also display 1D chain-like structure, but the nine-coordinate lanthanide centers bonded by four ligands. Luminescent property indicates that compound 4 exhibits photoluminescence in the solid state at room temperature.
- Yang, Juan,Hu, Rui-Xiang,Zhang, Man-Bo
-
p. 398 - 403
(2012/11/13)
-
- Comparison of covalency in the lanthanide chloride and nitrate complexes based on the adsorption data on zeolite y
-
The changes of the distribution constants Kd of lanthanide chlorides in the system: zeolite Y (solid phase)-sodium chloride (aqueous phase) were investigated. The evident tetrad effect in the change of log Kd values within the lantha
- G?adysz-P?aska, Agnieszka,Majdan, Marek,Ferenc, Wies?awa,Sarzyński, Jan
-
p. 469 - 474
(2012/03/22)
-
- Influence of sulfate ions on properties of co-precipitated Y 3Al5O12:Nd3+ nanopowders
-
A new precursor of yttrium aluminum garnet with an approximate composition of NH4AlY0.6(CO3)x(OH) y(SO4)z·nH2O has been synthesized via a reverse strike co-precipitation method with ammonium hydrogen carbonate as the precipitant and ammonium aluminum sulfate as the sulfate ions source. The evolution of phase, chemical composition and morphology of the precursor during calcination has been studied by means of XRD, XPS, DTA-TG, BET methods and FT-IR spectroscopy. The loosely agglomerated powders with narrow size distribution, spherical shapes and diameter of 50-60 nm have been obtained by calcination of the sulfate-containing precursor at 1100 °C for 2 h. The doping by sulfate ions enhances densification of Y3Al 5O12:Nd3+ nanopowders compared to undoped ones. This leads to improved microstructure and optical transmittance of vacuum sintered ceramics prepared from sulfate-doped nanopowders.
- Deineka,Doroshenko,Mateychenko,Tolmachev,Vovk,Vovk,Yavetskiy,Baumer,Sofronov
-
p. 200 - 205
(2011/01/06)
-
- Synthesis of Pb1-xRxZr0.65Ti 0.35O3 (x = 0.05, 0.10 and 0.15; R = Ce, Pr and Nd) powders by Gel Entrapment Technique and study on their thermo-physical and electrical properties
-
Rare earth doped lead zirconate titanate of composition (Pb 1-xRxZr0.65Ti0.35)O3 where x = 0, 0.10 and 0.15 and R = Ce, Pr and Nd was prepared by Gel Entrapment Technique (GET). The gel was suitably c
- Pai, Rajesh V.,Mishra,Pai,Mukerjee,Venugopal
-
p. 184 - 190
(2011/01/09)
-
- The sorption properties of carbon nanotubes modified with tetraphenylmethylenediphosphine dioxide in nitric acid media
-
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
-
p. 2223 - 2226
(2009/04/13)
-
- Mutual solubility between hexane and tri-n-butyl phosphate solvates of lanthanide(III) and thorium(IV) nitrates at various temperatures
-
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
-
p. 1144 - 1146
(2008/10/09)
-
- Synthesis, spectral studies, thermal decomposition kinetics, reactivity and antibacterial activity of some lanthanide(III) nitrate complexes of 2-(N-indole-2-one)amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene
-
Complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Dy(III), Yb(III) and Lu(III) with 2-(N-indoIe-2-one)amino-3-carboxyethyl-4,5,6, 7-tetrahydrobenzo[b]thiophene formed by the condensation of isatin and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene have been synthesized and characterized on the basis of elemental analysis, molar conductance measurements, magnetic susceptibility data and UV-vis, IR and NMR spectral studies. The spectral data reveal that the ligand acts as neutral tridentate coordinating to the metal ion through the azomethine nitrogen, ester carbonyl and carbonyl oxygen of the isatin moiety. Coordination number nine has been proposed for the complexes. The XRD pattern of the lanthanum(III) complex shows that the metal complex possesses tetragonal crystal lattice. The lanthanum(III) complex undergoes facile transesterification reaction when refluxed in methanol for a long period. Studies on antibacterial activity show that the complexes are more potent bactericides than the ligand.
- Thankamony,Mohanan
-
p. 247 - 251
(2008/02/12)
-
- Synthesis, characterization, thermal stability, reactivity, and antimicrobial properties of some novel lanthanide(III) complexes of 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene
-
Two series of new lanthanide(III) complexes of the type [Ln(HSAT) 2(H2O)3Cl3] and [Ln(HSAT) 2(NO3)3], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy, Tm, Yb, or Lu, and HSAT = 2-(N-salicy
- Mohanan,Devi
-
p. 600 - 609
(2008/10/09)
-
- Mutual solubility of the components in systems of decane with tri-n-butyl phosphate solvates of rare-element(III) (neodymium, gadolinium, yttrium, lutetium) nitrates at different temperatures
-
Phase diagrams of liquid binary systems formed by decane and tri-n-butyl phosphate solvates of rare-element(III) (neodymium, gadolinium, yttrium, lutetium) nitrates were studied at 273.15-315.15 K. The phase diagrams include a homogeneous solution region and a liquid-liquid phase separation region: phase I is enriched with decane, and phase II is enriched with [Ln(NO 3)3(TBP)3] (Ln = Nd, Gd, Y, Lu). The liquid-liquid phase separation regions in the binary systems decrease with rising temperature. The upper critical solution temperatures for the binary systems depend on the nature of rare-earth elements(III). Copyright
- Keskinov,Kudrova,Pyartman
-
p. 819 - 821
(2008/10/09)
-
- 123 phases formed in the YLnKCu3Ox. (Ln = La, Nd) systems
-
A 123 tetragonal phase with the doubled unit cell volume (the 336 phase), the unit cell parameters a = b = 0.5544(5) nm, c = 1.1958(8) nm, and a composition close to Y2Nd2.24K 1.76Cu6O14.1 [Z(Q) = 7.24], in which K occupies Ba positions, is prepared using routine nitrate technology. The synthesis of a similar phase containing lanthanum and potassium under the specified conditions failed. Copyright
- Stukan,Dudareva,Kil'yanov,Polyakova,Shashkin
-
p. 1485 - 1487
(2008/10/09)
-
- Yttrium and lanthanide nitrate complexes of 2,3-dimethyl-4-formyl(benzhydrazide)-1-phenyl-3-pyrazoline-5-one
-
Complexes of yttrium and lanthanide nitrates with the Schiff base 2,3-dimethyl-4-formyl(benzhydrazide)-1-phenyl-3-pyrazoline-5-one (L) have been synthesized and characterized by elemental analyses, electrical conductance in non-aqueous solvents and electronic as well as infrared spectra. The complexes have the general molecular formulae [Ln(L)2(NO3)]-(NO3)2 (Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho or Er). The ligand chelates with the metal ion in a neutral tridentate fashion through both carbonyl oxygens and the azomethine nitrogen in all of these complexes. One of the nitrate ions is monodentately coordinated and the other two remain as counter ions. A coordination number of seven is assigned to the metal in all of these complexes. The covalency parameters evaluated from solid and solution phase electronic spectra suggest weak covalent character of the metal-ligand bond.
- Ajithkumar,Radhakrishnan
-
p. 831 - 842
(2008/10/08)
-
- Yttrium and lanthanide nitrate complexes of 4-formyl-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one
-
Complexes of yttrium and lanthanide nitrates with 4-formyl-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one (FDPP) having the general formula [Ln(FDPP)2(NO3)2]NO3, where Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Er have been synthesised and characterised by elemental analyses, molar conductance in non-aqueous solvents, electronic, infrared and proton NMR spectra as well as thermogravimetric analyses. FDPP acts as a neutral monodentate ligand, coordinating through the ring carbonyl oxygen and two of the nitrate ions are coordinated in a bidentate manner. A coordination number of six may be assigned to the metal ion in these complexes. The covalency parameters evaluated from the solid state electronic spectra suggest weak covalent character of the metal-ligand bond. The TG data of the lanthanide complexes indicate that the complexes are stable up to about 170° C and undergo decomposition in two stages forming the respective anhydrous lanthanide oxide as the final product.
- Joseph, Siby,Radhakrishnan
-
p. 1077 - 1089
(2008/10/09)
-
- Investigations on structure and physical properties of some new members of the LaPd2O4 family
-
The new mixed valent oxopalladates MPd2O4 (M = Pr, Nd, Gd, Y) have been synthesized from the binary oxides in presence of a solid oxygen carrier (KClO3) by applying hydrostatic pressure (ca. 2 GPa). According to X-ray investigations these oxides crystallize in space groupe I41/a (No. 88) and are isotypic to LaPd2O4 (PrPd2O4: a = 5.8382(2), c = 10.1687(5) A?; NdPd2O4: a = 5.8419(3), c = 10.1949(6) A?; GdPd2O4: a = 5.7799(3), c = 10.0677(8) A?; YPd2O4: a = 5.7359(3), c = 9.9829(8) A?). The crystal structure consists of square planar PdO4 units which are stacked to form columnar arrangements along [100] and [010], respectively. The PdO4 squares are connected via common corners to a three-dimensional framework. By substitution of Pr3+, Nd3+, Gd3+ and Y3+ for lanthanum the Pd-Pd distances decrease and the electrical conductivities increase. The oxopalladates investigated in this work are black, paramagnetic and semiconducting. At ambient pressure they decompose at temperatures above 880 K into elemental palladium and the binary rare earth oxides. ? Johann Ambrosius Barth 1996.
- Kra?mer, Gerd,Ha?gele, Eugen,Wagner, Norbert,Jansen, Martin
-
p. 1027 - 1034
(2008/10/09)
-
- New trivalent lanthanide complexes of phthalate-containing hydrazinium cation - Preparation, and spectral and thermal studies
-
Several new lanthanide complexes of the types, (N2H5)2[Ln(C6H4(COO) 2)2.5], A, where Ln is La Eu except Pm, and N2H5[Ln(C6H4(COO)2) 2(H2O)3]-H2O, B, where Ln is Eu-Dy, have been prepared by crystallisation from concentrated aqueous solutions containing the metal nitrates and dihydrazinium phthalate in 1:6 molar ratio. The aqueous solutions of the compounds are acidic and exhibit high values of molar conductance. The complexes were characterised by analytical, magnetic, spectral, thermal and X-ray studies. The OCO- groups of phthalate bridge in both mono- and bidentate fashion as evidenced by IR data. The N-N stretching frequency in the region 960 965 cm-1 supports the non-coordination of N2H5+ ions. Both IR and thermal data confirm the presence of three coordinated and one lattice water molecules in the B complexes. Based on the results obtained, a nine-coordination for the lanthanide ions is proposed. Simultaneous TG-DTA of the complexes shows that they are thermally less stable and give metal oxides as the final product. X-ray powder patterns show isomorphism among the A and B complexes but not between them.
- Kuppusamy,Govindarajan
-
p. 143 - 155
(2008/10/09)
-
- Langmuir Film-Forming and Second Harmonic Generation Properties of Lanthanide Complexes
-
A series of amphiphilic lanthanide complexes were designed and synthesized, in which the lanthanide complex anions act both as the counterions of hemicyanine and as the spacer within a Langmuir-Blodgett (LB) film.Studies on the surface pressure-area (?-A) isotherms of these complexes show that the film-forming properties can be clearly improved if appropriate β-diketone ligands were chosen.The effects of molecular structures of the complexes, including the variation of lanthanide central ions, the structures of β-diketone ligands, and the length of alkyl chains in hemicyanines, on the film-forming properties of the materials are discussed.From second-harmonic generation experiments, the largely enhanced second-order molecular hyperpolarizability of lanthanide complexes with good film-forming properties were obtained compared with the hemicyanine iodide.This effect may be due in part to the local field effect but primarily molecular ordering and ordered segregation of hemicyanine chromophores by the bulky lanthanide complex anions.The charge separation of the hemicyanine chromophores was supported by the crystal structure of a model complex.The homogeneity of the film was verified by low angle X-ray diffraction and also by the linear relationship of the absorbance vs the number of layers of the LB films of a selected complex.
- Huang, Chunhui,Wang, Kezhi,Xu, Guangxian,Zhao, Xinsheng,Xie, Xiaoming,et al.
-
p. 14397 - 14402
(2007/10/02)
-
