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At room temperature solid electrolyte Li3−xSc2−xZrx(PO4)3 (x = 0, 0.1) compounds belong to monoclinic symmetry (space group P21/n) and the compound with x = 0.2 belongs to orthorhombic symmetry (Pbcn). At 900 K all the investigated compounds belong to orthorhombic symmetry (space group Pbcn). Anomalies of enthalpy, change of activation energy of ionic conductivity, anomalies of dielectric permittivity in the temperature range 420 K–660 K of investigated compounds with x = 0 and 0.1 were found. The phenomena are related to structure phase transition in the compounds. The relaxation dispersion regions were found in conductivity spectra for the all investigated samples. The frequency dispersion regions are caused by the relaxation processes in grain, grain – boundaries and electrodes. The temperature dependencies of the bulk conductivity and relaxation frequency in the bulk are governed by the same activation energy. It is shown that major role in the temperature dependence of bulk conductivity is played by Li+ ion mobility, which increases as temperature increases. [ABSTRACT FROM PUBLISHER]

The solid electrolyte Li2.9Sc1.9-yYyZr0.1(PO4)3 (where y = 0, 0.1) compounds belong to monoclinic symmetry (space group P21/n) at room temperature. The Zr 3d, Sc 2p, P 2p, Y 3d, O 1s, and Li 1s core level X-ray photoelectron spectra (XPS) were fitted. The Li ions in ceramics without Y occupy two different positions and in the ceramics with Y they occupy one position in the lattice. The deconvolutions of the Zr 3d, P 2p, Sc 2p, and Y 3d core level XPS are associated with different valence states on the surfaces of the investigated ceramics. Anomalies of enthalpy, change of activation energy of ionic conductivity, anomalies of dielectric permittivity in the temperature range 420-520 K of investigated compounds were found. The phenomena are related to diffuse structure phase transition in the compounds. At temperatures 600 and 900 K, the compounds belong to orthorhombic symmetry (space group Pbcn). [ABSTRACT FROM AUTHOR]

Abstract: The powders of Li1+y Ge2−x−y Ti x Al y (PO4)3 (x =0.1÷0.3, y =0.07÷0.21) have been synthesized by a solid phase reaction. The structure of the compounds was determined by X-ray diffraction patterns from the powder. The compounds belong to the rhombohedral symmetry (s. g. R3¯c) with six formula units in the lattice. The sintering of the Li1+y Ge2−x−y Ti x Al y (PO4)3 ceramics was conducted at temperature T =1363 K for 1 h in air. The ionic conductivity of the ceramics was investigated by impedance spectroscopy in the frequency range from 1 MHz to 1.2 GHz at temperatures from 300 K to 600 K. Two dispersions regions were found in ionic conductivity spectra for all the compounds. The dispersions are caused by the ion transport in grain boundaries and in grains of the ceramic samples. The substitution of Ge4+ →Ti4+, Al3+ leads to the changes in the structure parameters and electrical properties of the compounds. [Copyright &y& Elsevier]

Abstract: The solid electrolyte Li1.3Zr1.4Ti0.3Al0.3(PO4)3 compound was synthesized by a solid-state reaction. The ceramic samples were sintered 1, 2 and 3h and studied by X-ray and complex impedance spectroscopy in the frequency range from 106 to 1.2×109 Hz in temperature range from 300 to 600K. The investigated compound at room temperature belongs to rhombohedral symmetry (s.g. ) with six formula units in the lattice. Two regions of relaxation dispersion were found. The dispersions are related to the fast Li+ ion transport in the grain and grain boundaries of ceramics. Varying of the sintering time affects the density of the ceramics, the values of total conductivity and its activation energy. The values of grain conductivity, its activation energy, and relaxation frequency in grain, dielectric permittivity and dielectric losses are independent from sintering duration of the ceramics. The value of activation energy of grain conductivity and activation energy of relaxation frequency is the same. That can be attributed to the fact that the temperature dependence of the grain conductivity is caused only by the mobility of Li+ ions, while a number of charge carriers remains constant with temperature. [Copyright &y& Elsevier]

Abstract: The solid electrolyte Li2.8Sc1.8−y Y y Zr0.2(PO4)3 (where y =0, 0.1) compounds were synthesized by a solid state reaction and studied by X-ray diffraction. At room temperature the compounds belong to orthorhombic symmetry (space group Pbcn) with four formula units in the unit cell. Elemental compositions and binding energies of Zr 3d, Sc 2p, Y 3d, P 2p, O 1s, and Li 1s core level at Li2.8Sc1.8Zr0.2(PO4)3 and Li2.8Sc1.7Y0.1Zr0.2(PO4)3 ceramics’ surfaces have been determined by XPS. Impedance spectroscopy of the ceramics has been performed in the frequency range 10–3×109 Hz in the temperature interval 300–600K. The substitution of Sc by Zr and Y in the host compound Li3Sc2(PO4)3 leads to the increase of ionic conductivity of the new ceramics. [Copyright &y& Elsevier]

Abstract: The powder of Li1+ x + y Sc x Y y Ti2− x − y (PO4)3 (x =0.15–0.3, y =0.01–0.15) has been synthesized by solid phase reaction. The structure of the compounds was determined by X-ray diffraction patterns from the powder. The compounds belong to the rhombohedral symmetry (space group R3¯c) with Z =6 formula units in the lattice. Ceramic samples were sintered in air at temperature T s =1523 K varying sintering time (t s) from 1 to 5 h. The element compositions of ceramics were defined by XPS. The complex impedance (Z˜), electric conductivity (σ˜), dielectric permittivity (ɛ˜) of the ceramics in frequency range (106−1.2·109) Hz and temperature range (300−600) K were carried out. Two relaxation dispersions of the electric parameters were found for all compounds. The dispersions are caused by the ion transport in grains and grain boundaries of the ceramic samples. The values of the bulk (σ b), grain boundaries (σ gb) conductivities, their activation energies, and dielectric permittivity are dependent on stoichiometric parameters x, y and sintering conditions of the ceramics. [Copyright &y& Elsevier]

Abstract: It was shown in many literature sources that ionic conductivity of the LiTi2(PO4)3 compound was increased by several orders substituting Ti4+ ion by trivalent ions. In the case of substituting by La3+ there was no success to synthesize single phase material. The two phases were obtained and conductivity increased considerably. In the present work the substitution Ti4+ →La3++ Li+ in the LiTi2(PO4)3 system was studied by XRD, SEM, XPS, WDX, and impedance spectroscopy. The powder was prepared by solid state reaction with relative mixture of initial materials to obtain Li1+ x La x Ti2− x (PO4)3 with x =0.3, but the impurity of LaPO4 was detected by XRD. The ceramic samples were sintered with different sintering duration to check the influence of sintering on composition and electrical properties. [Copyright &y& Elsevier]

Abstract: Preparation and electrical characterization of NASICON-type compound, Li1.3Ge1.4Ti0.3Al0.3(PO4)3, are described. The solid solution is obtained with Ge4+ →Ti4+ and Ge4+ →Al3+ substitutions in LiGe2(PO4)3. The powder has been fabricated by a solid state reaction and the structural characteristics of it have been studied by X-ray. Ceramic samples have been sintered by varying the sintering duration from 1 to 3h. Samples were studied by complex impedance spectroscopy in the frequency range 1MHz–1.2GHz and temperature range 300–600K. Two regions of relaxation dispersion were found. The dispersions were related to the fast Li+ ion transport in the grains and grain boundaries. Variation of the sintering duration has no considerable effect on electrical properties of the ceramics. [Copyright &y& Elsevier]