Crystallization characteristics and properties of lithium germanosilicate glass-ceramics doped with some rare earth oxides

Abstract

Lithium disilicate glass-ceramic, modified by GeO2/SiO2 replacement to give 33.60Li2O-5.00GeO2-61.40SiO2 (mol%) composition, was investigated by the conventional melt technique. The effect of adding 0.1mol of some rare earth oxides like Y2O3, La2O3 or CeO2 on the crystallization behavior, chemical durability, Vicker's microhardness, and density of the obtained glass-ceramics were studied. The effect of In2O3 was also investigated. The glass transition temperature (Tg) was reduced slightly by the replacement of GeO2/SiO2, while it markedly increased when GeO2-containing glass was doped with different rare earth or In2O3 oxides. Different forms of disilicate phases like Li2Si2O5, Y2Si2O7 and La2Si2O7 in addition to two forms of Li2(Ge,Si)2O5 and Li2(Ge,Si)O3 solid solution were developed. LiInSi2O6 of pyroxene structure, Li6Ge8O19 and CeO2 phases were also detected. The density values of the glass-ceramics vary from 2.38 to 3.14g/cm3 and the hardness was in the range of 4150–5585MPa. The chemical durability of the modified glass-ceramics was greatly improved. The modification of glass-ceramics with GeO2 or other dopant oxides led to producing of materials with more dense and ultra-fine microstructures. Such materials are promising for superior applications as catalysis, electrolyte in fuel cells, biomedical, as well as dental restorative applications.