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Rhodium vanadate is an important catalytic compound and was synthesized by solid state reaction route and characterized by X-ray diffraction. To improve the performance of any device basic understanding of the microscopic mechanism is necessary. The X ray diffraction pattern was refined and the compound was found to crystallize in a tetragonal structure with space group P42/mnm. [ABSTRACT FROM AUTHOR]

In the present work, a novel polyaniline cerium vanadate nanocomposite was facilely prepared by in-situ polymerized sol-gel process. X-ray diffraction (XRD) pattern revealed the crystal planes and size of the synthesized nanocomposite. The morphological shape and the crystalline nature of the nanocomposite were examined by field emission scanning electron microscopy (FESEM). Fourier transform infrared spectroscopy (FT-IR) confirmed the conceivable stretching frequency on the surface of nanocomposite. Polyaniline cerium vanadate nanocomposite was used as a solid phase adsorbent for removing methylene blue (MB) from aqueous media. Besides, these nanocomposites evinced antimicrobial activity against E.coli and Staphylococcus aureus. The studies describing the synthesis of polyaniline cerium vanadate by simple in-situ polymerised sol-gel method followed by the investigation of adsorption and antibacterial activities may be useful for the research activities to open a new horizon in the field of nanotechnology. [ABSTRACT FROM AUTHOR]

In this paper, we have studied effect of catalyst (buffer layer) on structure, morphology, crystallinity, uniformity of nanostructured thin films deposited in nitrogen plasma ambient keeping all other process parameters constant. The process used for deposition is novel known as Plasma Assisted Sublimation Process (PASP). Samples were then studied using SEM, TEM, HRTEM, Raman spectroscopy. By structural analysis it was found out that samples deposited on Ni layer composed chiefly of α-V2O5 but minor amount of other phases were present in the sample. Samples deposited on Al catalyst layer revealed different phase of V2O5, where sample deposited on Ag was composed chiefly of VO2±x phase. Further analysis revealed that morphology of samples is also affected by catalyst. While samples deposited in Al and Ag layer tend to have reasonably defined geometry, sample deposited on Ni layer were irregular in shape and size. All the results well corroborate with each other. [ABSTRACT FROM AUTHOR]

The samarium doped NaCaVO4 phosphor was synthesized by the combustion method. The X-ray powder diffraction (XRD) analysis confirmed that the phosphor powder crystallized as orthorhombic structure belonging to space group Cmcm. From Williamson-Hall analysis the grain size and microstrain in the powder was estimated. The Fouriertransform infrared (FT-IR) studies further validated the formation of vanadate phase of the phosphor. Photoluminescence (PL) study revealed that the phosphor could be efficiently excited by UV-VIS from 200 nm to 500 nm. The 565 nm, 602 nm, 648 nm and 713 nm emissions were ascribed to 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2 and 11/2) transitions of the Sm3+ ion. The present material may be explored as a novel phosphor to be excited by UV light emitting diodes (LEDs) chips for solid-state lighting and display applications. [ABSTRACT FROM AUTHOR]

In this work, we present the electronic transport and optical properties of Te2V2O9 calculated under the purview of Density Functional Theory. For the first time, linear optical properties including dielectric function, refractive index, absorption coefficient, electronic energy loss spectra and also electronic transport properties were calculated by a self-consistent approach using the WIEN2k code. PBE exchange potential was used for the calculation of band structure. The transport properties were calculated using BoltzTraP code. [ABSTRACT FROM AUTHOR]

A structure-property relationship of semi-conducting 20BaO·10Fe2O3·xP2O5(70-x)V2O5 (BFPV) glass was investigated by 57Fe-Mo¨ssbauer spectroscopy, dc four-probe method, and leaching test using 20% HCl. Isothermal annealing of 10BFPV glass, carried out at 500 °C and for 1000 min, resulted in a marked increase in electrical conductivity from 7.4×10-6 to 1.3×10-2 S cm-1, while 50BFPV glass showed a slight decrease in electrical conductivity from 1.8×10-6 to 1.8×10-7 S cm-1. The dissolution rate decreased from 100 to 33.0% for the annealed 10BFPV glass under a leaching test using 20% HCl for 72 h, indicating enhancement of the chemical durability by addition of P2O5. These results imply that introduction of PVO4 units into vanadate glass is very effective to improve the chemical durability, and that the marked increase in electrical conductivity is directly related to the structural relaxation of FeIIIO4, VIVO4, and VVO4 units, as recently observed in 20BaO·10Fe2O3·xMnO2(70-x)V2O5 glasses. Mo¨ssbauer spectra of 10BFPV glass showed a marked decrease in quadrupole splitting (Δ) from 0.78 to 0.36±0.02 mms-1 after the isothermal annealing. This reflects a decreased distortion of FeIIIO4 tetrahedra or structural relaxation of 3D-network, since electric field gradient at the nucleus of high spin FeIII, caused by five-valence electrons equally distributed on five 3d-orbitals (eqval), is zero and, hence, eqlat caused by steric configuration of neighboring atoms is directly involved with Δ. It is considered that structural relaxation of FeIIIO4, confirmed by Mo¨ssbauer spectra analysis, is also the case for VIVO4 and VVO4 tetrahedra since they share corner oxygen atoms with FeIIIO4 tetrahedra. Increase in electrical conductivity from 4.7×10-5 to 3.8×10-2 S cm-1 and chemical durability, as demonstrated by a decrease in dissolution rate from 100 to 41.7 %, were also confirmed for annealed 20BaO·10Fe2O3·yWO3·(70-y)V2O5 (BFWV) glass. Thus, the electrical and chemical properties of vanadate glass can be successfully regulated by adding P2O5 or WO3. [ABSTRACT FROM AUTHOR]

In this paper we modeled the crystal field and spin-Hamiltonian parameters for tetrahedral coordinated Mn5+ doped in Li3VO4 host matrix. The numerical theoretical crystal field parameters were computed with C3v site symmetry of the Mn5+ impurity ions, in the frame of the superposition model of crystal field, taking into account the effects of the bond formation between the Mn5+ and first coordination sphere of O2- ions coordination. The Hamiltonian of the Li3VO4: Mn5+ system has been diagonalized in a complete basis set spanned by all wave functions of the 3d2 electron configuration. The obtained results give a satisfactory agreement with experimental data. The spin-Hamiltonian parameters of the system (g|, g⊥ factors and for D zero field splitting energy) are calculated in perturbation theory method, and good agreement with experimental data is obtained. [ABSTRACT FROM AUTHOR]

In this contribution, we report the non-Arrhenius behaviour (nAB) in the temperature-dependent dc conductivity of silver ion conducting vanadate, alkali ion conducting borate and silicate glasses well below their glass transition temperature. The temperature-dependent dc conductivity shows the strong departure from the Arrhenius behaviour in the studied glasses. In the case of silver ion conducting glasses, the nAB depends strongly on the silver halide content and on the type of the halide anion. From the frequency dependence of the conductivity, we draw conclusions on the origin of the nAB. In contrast to the silver ion conducting glasses, alkali ion conducting borate and silicate glasses show the positive curvature in the Arrhenius plot. These results are the manifestation of local structural changes of the borate and silicate network with temperature, and give rise to different local environments into which the alkali ions hop. Furthermore, the present study provides new insights into the strong link between the dynamics of the alkali ions and different sites associated with it in the glassy materials. [ABSTRACT FROM AUTHOR]

Birefringent ND:YVO4 pumped by diode laser with fundamental wavelength of 1064 nm was used to pump nonlinear KTP crystal. Quartz crystals having natural birefringent property namely quarter and half waveplates were conducted in conjunction with the bulk of KTP to enhance the nonlinear beam. The result showed that half waveplate have electrical to optical conversion efficiency of 15.6 mW/A as compared to quarter waveplate is only 8.74 mW/A. The threshold current for SHG is found 5.3 A with half waveplate and 5.9 A with quarter waveplate. The high performance shown by half waveplate is realized due to the good mode matching after converting the polarization state. [ABSTRACT FROM AUTHOR]

Phospho-vanadate glasses containing various compositions of bismuth oxide were synthesized by melt quenching technique. Electrical conductivity has been measured over a wide range of temperature (373K-480K) and frequency (40 Hz -10 MHz) range. The data have been analyzed in the light of polaronic hopping model. The total conductivity at all the frequencies is due to both polarons and Bi2O3. It is seen that the conductivity increases with Bi2O3 content indicating that there is ionic contribution to the total conductivity in addition to electronic. The exponent 's' obtained from the power law in these glasses shows temperature dependence, which is attributed to high degree of modification in the glass network. [ABSTRACT FROM AUTHOR]

I give a brief overview of a polaron formation in three distinct transition metal oxides: (i) spin polaron when a hole is added to the antiferromagnetic (AF) ordered plane in La2CuO4, (ii) orbital polaron when a hole is added to the alternating orbital (AO) ordered plane in LaMnO3, and (iii) spin-orbital polaron when a hole is added to the AF and AO ordered plane in LaVO3. Comparison of the distinct features of the above polarons can shed some light on the basic differences between the experimental phase diagrams of the lightly doped transition metal oxides La2-xSrxCuO4, La1-xSrxMnO3, and La1-xSrxVO3. [ABSTRACT FROM AUTHOR]

The new complex Pb based vanadate, NaPb2V5O15 (NPV), of tungsten bronze structure was synthesized by a solid state reaction technique realized at low temperature, (i.e.,550°C). The X-ray diffraction analysis shows that the sample has orthorhombic structure at room temperature. The SEM micrograph of NPV shows that the grains are homogeneously distributed throughout the sample. The dielectric and impedance properties of NPV, measured in a wide frequency (102–106Hz) and temperature (room temperature-500°C) range show that the compound exhibits phase transition at 210°C (10 kHz). The ac electrical conductivity (σac) of the material was found to be temperature dependent. [ABSTRACT FROM AUTHOR]

We formulate the double exchange (DE) model for systems with t2g orbital degeneracy, relevant for hole-doped cubic vanadates. In the relevant regime of strong on-site Coulomb repulsion U we solve the model using two distinct mean-field approximations: Hartree-Fock, and mean-field applied to the formulation of the model in the Kotliar-Ruckenstein slave boson represenation. We show how, due to the relative weakness of the DE mechanism via t2g degenerate orbitals, the anisotropic C-type antiferromagnetic metallic phase and the orbital liquid state can be stabilized. This is contrasted with the DE mechanism via eg degenerate orbitals which stabilizes the ferromagnetic order in the hole-doped regime of manganites. The obtained results are in striking agreement with the observed magnetic structures and the collapse of the orbital order in the doped La1-xSrxVO3, Pr1-xCaxVO3 and Nd1-xSrxVO3. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The R9Dy(VO4)7 [R = Sr and Ba] phosphors has been successfully synthesized by high temperature solid state reaction and characterized by XRD as well as photoluminescence measurements. The characteristic of Dy3+ emission was observed in R9Dy(VO4)7 [R = Sr and Ba] phosphors. Photoluminescence (PL) emission results shows the blue and yellow sharp bands at 480 nm and 575 nm for R9Dy(VO4)7 [R = Sr and Ba] phosphor s respectively at the excitation wavelength of 348 nm which is NUV excitation. Thus these phosphors may be applicable for the NUV excited solid state lighting devices as well as white LEDs. [ABSTRACT FROM AUTHOR]

The output of diode laser pumped 0.5 at % Nd doped vanadate YVO4 crystal bar was characterized. Diode laser has wavelength centered at 808 nm. The pump power was focused to localize the high power density of source at the crystal bar surface. The output of diode pumped vanadate crystal was detected by a spectrum analyzer. The output radiation is centered at 1064 nm with linewidth of 1.15 nm. The stimulated emission cross section was estimated to be 14.94×10-19 cm2. The intensity of the fluorescent beam was measured by powermeter and permanently recorded by using CCD video camera. The beam spot is TEMoo mode with beam divergence of 0.4° with the absent of intracavity. The optical -to-optical slope efficiency is found to be as 4.8% with threshold power of 1404 mW. [ABSTRACT FROM AUTHOR]

AC Conductivity measurements have been used to study the transport properties of PbI2 doped silver boro-vanadate glasses prepared by melt quenching technique. The samples are characterized by XRD and DSC measurements. A correlation between Rτ, the decoupling index and σdc has been observed. The observed conductivity values suggest enhancement in conductivity by the introduction of PbI2 salt in the host glass matrix. [ABSTRACT FROM AUTHOR]

We present the low temperature specific heat of the rare earth orthovanadate Pr1-xLaxVO3 computed by the means of a Modified Rigid Ion Model (MRIM) in a wide doping range (0 ≤ x ≤ 1). Also, the effect of La doping and the impact of lattice distortions on the elastic, cohesive and thermal properties of PrVO3 have been studied by an atomistic approach. The computed results are in good agreement with the available experimental data. The results can further be improved by incorporating the spin and orbital ordering contributions to the specific heat. [ABSTRACT FROM AUTHOR]

Lithium manganese vanadate and lithium nickel vanadate has been synthesized by using sol-gel method. XRD analysis reveals the samples posses orthorhombic and cubic structure. Scanning electron microscopic studies show the morphology of the both compound. The bulk conductivities of the samples are found to be 1.92 × 10-5 and 7.34 × 10-5 Scm-1 at room temperature. [ABSTRACT FROM AUTHOR]

Elastic properties of xLi2SO4-16 Li2O-(84-x) [0.7 B2O3-0.3 V2O5] where (5≤x≥30) glasses have been prepared by melt quenching method and structural investigations were carried out using ultrasonic pulse echo overlap technique at a frequency of 10 MHz and at 300 K. The molar volume increases and the density decreases with the increase of Li2SO4 concentration due to the incorporation of SO42- ions into the modified macromolecular network. The addition of Li2SO4 content leads to loose packing structure which is attributed to volume increasing effect and the reduction in the vibrations of borate and vanadate lattices. Increase in Li2SO4 results in decreasing cross link density which in turn decreases elastic moduli. The results are discussed in view of its network structure. The structural groups [VOO3/2]0 and [BO3/2]0 modify preferentially. This preference in modification is decided by the electronegativity (χ) of the structural groups. [ABSTRACT FROM AUTHOR]

Frustrated systems are interesting because of the associated degenerarate ground states. AlV2O4 is a typical charge frustrated system due to the multiple valency on Vanadium ion. It relieves its frustration through a structural transformation from cubic spinel to rhombohedral structure. Present work describes synthesis, structural characterization and high temperature powder XRD studies on AlV2O4. Preliminary magnetization measurements indicate deviations from Curie-Weiss behaviour indicating a possible presence of spin glass like ordering of the spins even after the charge frustration is relieved. [ABSTRACT FROM AUTHOR]

We report here inelastic neutron scattering, lattice dynamics calculations and relative high pressure stability of LuVO4. We have developed transferable interatomic potentials to study the lattice dynamics and model the experimentally obtained phonon density of states in LuVO4. The parameters of the theoretical interatomic potential have been fitted with respect to experimentally available Raman and infrared frequencies and equilibrium structure. We have also studied the stability of the zircon structure at ambient temperature with increasing pressure. We find that zircon phase (I41/amd) goes into a scheelite phase (I41/a) at around 8 GPa which is in excellent agreement with reported value of 7.9 GPa. [ABSTRACT FROM AUTHOR]

Lithium manganese vanadate (LiMnVO4) has been prepared by a sol-gel method. XRD analysis reveals that the prepared sample possess orthorhombic structure. Laser Raman spectrum shows the local environment of cations vibrational modes with respect to neighboring oxygen atom. The ionic conductivity of the sample is found to be 8.5×10-5 S cm-1 at 350 °C. [ABSTRACT FROM AUTHOR]

This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of [BO4/2]- and [B2V2O9]2-) groups are confirmed by Infrared Spectroscopy of investigated glasses. [ABSTRACT FROM AUTHOR]

Glasses in the system xLi2SO4-20Li2O-(80-x) [80P2O5-20V2O5] (5>=x>=20 mol%) has been prepared by melt quenching method. Dc and ac conductivity has been studied over a wide range of frequency (10 Hz to 10 MHz) and temperature (298 K-523 K). The dc conductivity found to increase with increase of Li2SO4 concentration. The ac conductivities have been fitted to the Almond-West type single power law equation σ(ω) = σ(0)+Aωs where 's' is the power law exponent. The ac conductivity found to increase with increase of Li2SO4 concentration. An attempt is made to elucidate the enhancement of lithium ion conduction in phosphor-vanadate glasses by considering the expansion of network structure. [ABSTRACT FROM AUTHOR]

A theory of doped vanadium oxides with long-range spin and t2g orbital orders is presented. The spin, orbital and quasi-particle excitations are calculated by the Schwinger-boson approach associated with the self-consistent Born approximation. It is shown that the quasi-particle spectra associated with the t2g orbital excitations are remarkably different from those of the spin excitations as well as those of the eg orbital excitations. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]