X-ray study of glassy, glass-ceramic, and polycrystalline LiNaGe4O9

Abstract

X-ray diffraction was used to study the phase compositions of lithium tetragermanate LiNaGe₄O₉ glass and states obtained through its heating and crystallization. LiNaGe₄O₉ glass was obtained by quenching the melt. The amorphous-crystalline samples were prepared by isothermal heat treating at the temperatures chosen between the glass transition T_g = 783 K and devitrification T_C = 829 K points. The polycrystalline samples were obtained by heating the glass well above T_C. It was shown that in the glassy samples amorphous phase occupied about 92% of the whole volume, whereas the rest (~8%) fell on regions with ordered structure. In the amorphous-crystalline samples, disordered and ordered regions each occupied about half of the volume. In the polycrystalline samples, ordered regions occupied near 96% of the sample volume. The average size of ordered regions in the glass and amorphous-crystalline samples was estimated about 35 nm. In the polycrystalline samples, crystallites notably grew and had linear size near 120 nm. The obtained data demonstrate that controlled glass crystallization represents an effective way to prepare nanometer size structured solids.