Low-temperature sintering and densification kinetics of sol-gel derived lithium-mica glass-ceramics through MgF2 addition

摘要

The aim of the current research is to investigate the low-temperature sintering of a nano-crystalline lithium-mica glass-ceramic. Sol-gel technique was used to prepare the glass-ceramics by application of LiMg3AlSi3(1+x)O10+6xF2 with various x values (0.25, 0.5, 0.75, and 1) and different amounts of MgF2 as the sintering aid. Use of appropriate amounts of additive and stoichiometric deviation (x) decreased the sintering temperature to 750 degrees C. Results also revealed that the highest relative density was achieved by applying the optimal amount of additive (4 wt%) with x = 1. The densification activation energy for the glass-ceramic containing 4 wt% MgF2 was calculated as 214.33 +/- 17 kJ mol(-1); it was lower than the sample containing 5 wt% additive; hence it was confirmed as optimal content. Consequently, considering densification and phase analysis, true optimum amounts of MgF2 were determined as 4, 4, 3 and 1 wt% for the glass-ceramics synthesized with x = 1, 0.75, 0.5 and 0.25, respectively.