Electrical Transport Properties Of Iodine Oxide Phosphate Glasses Issued From The NaI-Li2O-WO3-P2O5 System

This work concerns the investigation of ion transport behaviour of NaI containing lithium tungsten phosphate glasses in order to understand better the role of NaI in the ionic cation transport. Glasses obtained in the system 0.5[x(2NaI)-(1-x)Li2O]-0.5[0.25(WO3)2-0.75P2O5] were investigated. The glass samples have been characterised using powder X-ray diffraction (XRD), thermal analysis, density and impedance spectroscopy. X-ray diffraction and thermal studies have confirmed that these glasses can be formed in the range x = 0 to 1. The mixed alkali glasses have shown higher activation energies and lower conductivities compared to single alkali doped glasses and this has been attributed to a mixed alkali effect.This work concerns the investigation of ion transport behaviour of NaI containing lithium tungsten phosphate glasses in order to understand better the role of NaI in the ionic cation transport. Glasses obtained in the system 0.5[x(2NaI)-(1-x)Li2O]-0.5[0.25(WO3)2-0.75P2O5] were investigated. The glass samples have been characterised using powder X-ray diffraction (XRD), thermal analysis, density and impedance spectroscopy. X-ray diffraction and thermal studies have confirmed that these glasses can be formed in the range x = 0 to 1. The mixed alkali glasses have shown higher activation energies and lower conductivities compared to single alkali doped glasses and this has been attributed to a mixed alkali effect

High-pressure study of the Sr2CoWO6 ordered double perovskite tungstate oxide.

Using synchrotron radiation and Raman spectroscopy and a diamond anvil cell we measured the pressure dependence of the lattice parameters and Raman modes of polycrystalline Sr2CoWO6. Angle-dispersive X-ray diffraction patterns were indexed and showed that at 2.2 GPa, the material transforms from the I4/m tetragonal structure to the P2(1)/n monoclinic structure. For pressure values between 2.2 and 12.7 GPa only monoclinic symmetries were found. We had difficulties with the convergence of the profile matching of the diffractogram. taken at 12.7 GPa, indicating that the second phase-transition took place. To get more informations about these structural changes, an in-situ Raman spectroscopic study was conducted to explore the pressure-induced phase-transition sequence of Sr2CoWO6 to pressures of 40.8 GPa at room-temperature. Group theory yields nine Raman-active modes for Sr2CoWO6 (I4/m), all the predicted bands are observed at ambient conditions (phase I). The experimental results indicate that structural changes are observed at 2.15 and 11.15 GPa, which we attribute to phase transitions; thus, giving rise to two new phases, named as phase II and phase III, respectively. In the 9.33-14.84 GPa interval a coexistence of phases II and III is observed. © 2007, Elsevier Ltd

Synthesis and X-ray characterization of Li(1–2x)NixTiO(PO4) (0<=x<=0.50)

Li(1–2x)NixTiO(PO4) oxyphosphate powders were prepared from dilute solutions of NiCl2·6H2O, Li2CO3, (NH4)2HPO4, and TiCl4 in ethanol. The final temperature was 850 °C. Li(1–2x)NixTiO(PO4) oxyphosphates with 0<=x<=0.10 crystallize in the orthorhombic system with space group Pnma, while those with 0.1

Some Physical, Chemical and Electrical Properties of the Polyphosphate LiMII 2(PO3)5 (M=Cu, Zn, Cd, Ba, Pb) Glasses

The polyphosphate glasses with the general formulae LiMII 2(PO3)5 (M=Cu, Zn, Cd, Ba, Pb) were prepared by using the melt-quench technique. They are characterized by X-ray diffraction (XRD), density measurements and differential thermal analysis (DTA). The results show that the glass transition temperature and molar volume increase nonlinearly with increasing of the bivalent cation atomic weight in the sequence Cu&lt;Zn&lt;Cd&lt;Pb&lt;Ba. Measurements of the ionic conductivity were made in the frequency range of 20 - 106 Hz and the temperature range 25 - 300°C. It is found that the Conductivity of the LiZn2(PO3)5 and LiCu2(PO3)5 glasses are much lower than those of the other samples. The differences in conduction properties are discussed based on the structural and atomic properties of the glass components

Rietveld refinements of the solid solution Li(1-2x)NixTiO(PO4) (O ≤ x ≤ 0.50).

Li(1−2x)NixTiO(PO4) oxyphosphates with 0 ≤ x ≤ 0.10 crystallize in the orthorhombic system with the space group Pnma, those with 0.10 < x ≤ 0.25 crystallize in the monoclinic system with the space group P21/c and compositions with 0.25 < x < 0.50 present a mixture of the limit of the solid solution Li0.50Ni0.25TiO(PO4) and Ni0.50TiO(PO4). The structure of the compositions 0 ≤ x ≤ 0.25 is based on a three-dimensional anionic framework constructed of chains of alternating TiO6 octahedra and PO4 tetrahedra, with the lithium and nickel atoms in the cavities in the framework. The dominant structural units in the compositions are chains of tilted corner-sharing TiO6 octahedra running parallel to one of the axis. The oxygen atoms of the shared corners, not implied in (PO4) tetrahedra, justify the oxyphosphate designation. Titanium atoms are displaced from the geometrical center of the octahedra resulting in alternating long (≈2.25 Å) and short (≈1.71 Å) Tisingle bondO(1) bonds. The four remaining Tisingle bondO bond distances have intermediate values ranging from 1.91 to 2.06 Å

Compression behavior of TaC0.98 under nonhydrostatic13; and quasi-hydrostatic pressures up to 76 GPa

Powder samples of TaC0.98 sandwiched between aluminum disks were placed in a rhenium gasket and compressed in a diamond anvil cell. The X-ray diffraction patterns were recorded under pressures up to 50 GPa using synchrotron radiation. The presence of aluminum in the cell rendered the sample pressure nearly hydrostatic and also served as the pressure standard. In another set experiments,TaC0.98 powder mixed with small quantity of platinum powder was placed in stainless steel gasket and compressed between the anvils. The X-ray diffraction patterns were recorded up to 76 GPa. In absence of any pressure-transmitting medium, the stress state of the sample was expected to be highly nonhydrostatic. The diffraction data were analyzed using lattice strain theory to estimate, the difference between the axial and radial stress components in the sample. The magnitudes of t suggest that the lower limit13; of compressive strength of TaC0.98 increases with increasing pressure and reaches -11 GPa at 76 GPa pressure. No phase transformation was observed up to the highest pressure. The bulk modulus and its pressure derivative derived from the volume-compression-pressure data are 345(9) GPa and 4.0(4), respectively

Some Physical, Chemical and Electrical Properties of the Polyphosphate LiMII2(PO3)5 (M=Cu, Zn, Cd, Ba, Pb) Glasses

The polyphosphate glasses with the general formulae LiMII 2(PO3)5 (M=Cu, Zn, Cd, Ba, Pb) were prepared by using the melt-quench technique. They are characterized by X-ray diffraction (XRD), density measurements and differential thermal analysis (DTA). The results show that the glass transition temperature and molar volume increase nonlinearly with increasing of the bivalent cation atomic weight in the sequence Cu&lt;Zn&lt;Cd&lt;Pb&lt;Ba. Measurements of the ionic conductivity were made in the frequency range of 20 - 106 Hz and the temperature range 25 - 300°C. It is found that the Conductivity of the LiZn2(PO3)5 and LiCu2(PO3)5 glasses are much lower than those of the other samples. The differences in conduction properties are discussed based on the structural and atomic properties of the glass components

Synthesis and X-ray characterization of Li(1–2x)NixTiO(PO4) (0<=x<=0.50)

Li(1–2x)NixTiO(PO4) oxyphosphate powders were prepared from dilute solutions of NiCl2·6H2O, Li2CO3, (NH4)2HPO4, and TiCl4 in ethanol. The final temperature was 850 °C. Li(1–2x)NixTiO(PO4) oxyphosphates with 0<=x<=0.10 crystallize in the orthorhombic system with space group Pnma, while those with 0.1

Structural, magnetic and magnetocaloric properties of layered perovskite La1.1Bi0.3Sr1.6Mn2O7

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