Search

The Li4xTi1-xP2O7(x = 0, 0.06, 0.1, 0.2) powders have been synthesized by the solid state reaction and their ceramics have been sintered. The Li4xTi1-xP2O7(x = 0.06, 0.1, 0.2) compounds have cubic superstructure 3×3×3 (space group Pa-3), which is also typical for TiP2O7pyrophosphate. The electrical properties of the ceramics were investigated in the frequency range of 10 to 3·109Hz and temperature interval of 400–720 K by impedance spectroscopy. The relaxation dispersion region in the conductivity and dielectric permittivitty spectra of Li4xTi1-xP2O7(x = 0, 0.06, 0.1, 0.2) ceramics was found. [ABSTRACT FROM AUTHOR]

LiFeP2O7and Li0.9Fe0.9Ti0.1P2O7were synthesised by solid-state reaction and ceramics were sintered. The structure of compounds was studied in the temperature range 300–700 K by X-ray diffraction. Ceramics’ surfaces were investigated by scanning electron microscope. Binding energies of Fe 2p, P 2p and O 1s core levels at ceramics’ surfaces have been determined by X-ray photoelectron spectroscopy and different valence states of Fe and P were detected. Elemental compositions of the compounds were studied by energy dispersive X-ray spectrometer. Impedance spectroscopy was performed in the frequency range 10 Hz–3 GHz and in the temperature interval 400–700 K. The changes of the activation energy of ionic conductivity at 528 and 550 K for LiFeP2O7and Li0.9Fe0.9Ti0.1P2O7, respectively, were found. The phenomena can be related to disordering in the unit cells of the compounds. [ABSTRACT FROM AUTHOR]

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]