Non-isothermal crystallization of LiNaGe4O9 glass

Abstract

The glass of lithium-sodium tetragermanate LiNaGe4O9 is crystallized on heating under the control of differential scanning calorimetry and thermal gravimetric analysis. The measurements were prepared in the temperature range 300-870 K and showed the relatively weak endothermic DSC anomaly and 40-50 K above the single exothermic peak. The endothermic anomaly observed at Tg testified to softening the glass structure whereas the exothermic peak at TC manifested crystallization of the amorphous phase. Studying of TGA demonstrated smooth nearly linear dependences without any visible anomalies. Varying the heating rate from 1.2 up to 40 K/min resulted in noticeable increase of the characteristic temperatures Tg and TC. Lower limit of the glass transition temperature Tg0 was estimated with the help of the existing model. The mechanism of the LiNaGe4O9 glass crystallization is discussed.

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

“…The partially crystallized amorphous-crystalline samples were prepared by isothermal heat treatment at T = 794 K for 20 minutes. This temperature was chosen within the interval between the glass transition temperature Tg = 783 K and the point TC = 829 K, above which complete crystallization was detected in DSC experiment [7][8][9]. After the heat treatment the partially crystallized sample became a bit cloudy.…”

“…We used the same approach for LNG composition. We quenched the melt and obtained LNG glass, and then, using the data of differential scanning calorimetry (DSC) we heat treated amorphous-crystalline and polycrystalline LNG [7][8][9]. For the following study, it is necessary to obtain as complete information as possible on phase composition and morphology of the samples prepared.…”