Crystallization features in stoichiometric glassy Li2Ge4O9: (a) DTA curve of the as-quenched sample. The measurement was performed at a heating rate of 10 K/min. (b) Photograph of the glassy samples subjected to isothermal heat treatments at 510 °C−590 °C for 1 h.
Powder XRD patterns of typical isothermal samples. The JCPDS data for the Li2Ge4O9 phase (#37−1363) is also included.
FE-TEM images of the glassy samples obtained by isothermal treatments at different temperatures for 1 h. images of the isothermal samples annealed at 510 °C (a), 520 °C (b), 530 °C (c), 540 °C (d), 550 °C (e), and 590 °C (f), together with the corresponding ED patterns are shown. Semicircular diffraction patterns of the GeO2 and Li2Ge4O9 phases, which are referred to JCPDS cards 36-1463 and 37-1363, are also included. The selected area electron diffraction pattern of the sample at 530 °C (g) is also displayed, and the diffraction spots were assigned to Miller indices of the stoichiometric phase of Li2Ge4O9.
FE-TEM images of the glassy samples obtained by nonisothermal treatments at a heating rate of 10 K/min; samples T x1, T p1, T x2, and T p2 correspond to (a)–(d), respectively. The ED patterns are also included in the corresponding images. The diffraction rings of samples T p1 and T x2/T p2 were identified as those of GeO2 and Li2Ge4O9 phases, respectively, on the basis of the JCPDS data. An extended image for sample T x2 (e) is also displayed.
Raman scattering spectra for the as-quenched glass and the isothermal samples annealed at 520 °C and 530 °C for 1 h.
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