Thermal properties and crystallization of lithium–mica glass and glass-ceramics

The purpose of this study was the synthesis of two groups of Li–mica glass-ceramics denoted by lepidolite (Al2.5F2KLi1.5O10Si3) and Li-phlogopite (LiMg3AlSi3O10F2). The studied system was SiO2–Al2O3–MgO–K2O–Li2O. A total of 3 compositions were prepared. Bulk casted glasses and sintered glass-ceramics of Li-phlogopite and lepidolite systems, were prepared. Eucryptite and virgilite were two prior phases of lepidolite and Li-phlogopite crystallization. It was shown that the obtained glass-ceramics have lower TEC than corresponding glasses. Sinterability of lepidolite glass-ceramic was shown that improved by increasing the Al2O3 content in glass composition. TEC and microhardness values were α = 6.08 × 10−6/°C, 755 ± 11.1, α = 7.86 × 10−6/°C, 739 ± 7.4 and α = 5.05 × 10−6/°C, 658 ± 6.2 HV for Li-lep, Klep1 and Klep2 glasses, respectively.