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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 powders of Li1.3Sc0.15Y0.15Ti1.7(PO4)3 were synthesized by a solid phase reaction. The sintering duration of the ceramic samples was varied from 0.25 h to 3 h and studied by X-ray and impedance spectroscopy in the frequency range from 10 Hz to 1.2×109 Hz at temperatures up to 600 K. Two relaxation dispersions of the electrical parameters were found and analysed in terms of bulk and grain boundary ionic transport processes. Varying of the sintering duration affects the density of the ceramics, sizes of grains, values of the total conductivity (σ t) and its activation energy (ΔE t). The bulk conductivity (σ b) and its activation energy (ΔE b) in average do not depend on duration of sintering. [Copyright &y& Elsevier]

The solid electrolyte Li1+2xMgxTi2−xP3O12 compounds were synthesized by a solid state reaction. The ceramic samples were sintered for 0.2, 0.5, 1 and 3 h and studied by X-ray and complex impedance spectroscopy in the frequency range 10 Hz–1.2 GHz in the temperature range 300–600 K. Two regions of relaxation dispersion were found, the dispersions were related to the fast Li+ ion transport in the bulk and grain boundaries. Varying of the sintering time affects the density, values of grain boundary conductivity (σgb), its activation energy (ΔEgb) and relaxation frequency (fgb). The activation energy (ΔEb) of bulk conductivity (σb) and activation energy (ΔEf) of relaxation frequency (fb) in the bulk are the same. That can be attributed to the fact that the temperature dependence of the bulk conductivity is caused only by the mobility of the fast Li+ ions, while a number of charge carriers remains constant with temperature. [Copyright &y& Elsevier]

Abstract: Li1.3AlyYx−yTi1.7(PO4)3 (x=0.3; y=0.1, 0.2) solid electrolyte compounds were synthesized by solid state reaction and studied by X-ray diffraction. At room temperature the compounds belong to a rhombohedral symmetry (space group Rc) with six formula units in the unit cell. Ti 2p, O 1s, P 2p, Li 1s, Y 3d, and Al 2p core level XP spectra at Li1.3AlyYx−yTi1.7(PO4)3 (x=0.3; y=0.1, 0.2) ceramic surfaces have been determined by XPS. The measurements of the electrical properties of the ceramic samples in the frequency range 10Hz–1MHz were carried out by a two probe method and a four probe method. The measurements in the microwave range (3·105–3·109 )Hz were performed in a coaxial line, the part of the inner conductor which was replaced by the sample. The investigation of the electrical properties of the ceramic samples was carried out in air in the temperature range (300 to 700)K. The increase of the stoichiometric factor y of the compounds leads to the increase in the total and bulk conductivities of ceramics and decreases their activation energies. [Copyright &y& Elsevier]

Abstract: The powder of Li1+xAlyScx−yTi2−x(PO4)3 with x=0.3 and y=0.1, 0.15, 0.2 has been prepared by solid state reaction and the ceramics have been sintered. The results of X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and impedance spectroscopy up to 109 Hz are presented. At room temperature the compounds belong to the rhombohedral symmetry (space group R3̅c). Ti 2p, P 2p, O 1s, Sc 2p, Al 2p, and Li 1s core level XP spectra''s were fitted. The values of binding energies of core level XP spectra''s, splitting energies of Ti 2p3/2–Ti 2p1/2, Sc 2p3/2–Sc 2p1/2, P2p3/2–P2p1/2 spin-orbit doublets, and amount of the elements with different binding energies were found to be dependent on stoichiometric factor y. The elemental compositions are defined by EDX. Impedance spectroscopy study in the frequency range 10Hz–3GHz have shown three relaxation dispersion regions of electrical properties and the processes are thermally activated. The high frequency dispersion region may be attributed to the relaxation processes in bulk, while lower dispersion regions are related to the processes in grain boundaries and blocking Pt electrodes. [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]