Ionic Conductivity in Multiphase Li2O-7GeO2 Compounds
O.O. Nesterov a, M.P. Trubitsyna, S.G. Nedilko b, M.D. Volnianskii a, S.M. Plyaka a and Ya.O. Rybak b
aOles'Honchar Dnipro National University, prosp. Gagarina 72, Dnipro, 49010, Ukraine
bTaras Shevchenko National University of Kyiv, 64/13 Volodymyrska Str., Kyiv, 01601, Ukraine
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Crystallization of Li2O-7GeO2 glass was carried out on heating, simultaneously differential scanning calorimetry and electric properties were studied. Morphology of the phase states obtained at glass devitrification was examined by atomic force microscopy. It was shown that amorphous phase of Li2O-7GeO2 was crystallized in stages through the intermediate state with increased conductivity σ . In the intermediate state the sample volume was occupied by nanometer-sized nuclei with ordered structure surrounded by internuclear amorphous medium. Complete glass crystallization occurred through transformation of nanometer-sized nuclei into micrometer-sized crystallites and was accompanied by a sharp and irreversible decrease of conductivity. Atomic force microscopy of the samples heat-treated in different ways showed that Li2O-7GeO2 glass crystallization was suppressed near the surface and mainly proceeded within the sample bulk. Charge transfer in amorphous, nanocrystalline intermediate and polycrystalline phases of Li2O-7GeO2 was associated with motion of the weakly bound Li ions.

DOI: 10.12693/APhysPolA.133.864
PACS numbers: 61.43.-j, 66.10.Ed, 77.84.-s, 68.37.Ps