The effect of aluminum sources on synthesis of low expansion glass–ceramics in lithia–alumina–silica system by sol–gel route

This paper investigated the effect of different aluminum sources on the crystallization behaviors, thermal expansion and morphology of lithium aluminosilicate glass–ceramics sintered at different temperatures. Specimens were prepared by sol–gel technology. The crystalline phase in the specimen with Al(NO3)3⋅9H2O aluminum source sintered at 1300 °C has shown a major phase of Li2Al2Si3O10 accompanied by minor phase of LiAl5O8 and trace amount of SiO2. The β-eucryptite appeared as the only phase in the specimens with aluminum isopropoxide or aluminum isopropoxide mixed with Al(NO3)3⋅9H2O aluminum sources sintered at 1300 °C. The sintering temperature has significant effect on the thermal expansion behavior of all the specimens. SEM indicated that microstructures were spherulitic crystals and no distinct differences were observed in the specimens with different aluminum sources.