Thermal Expansion Properties of Some Synthetic Lithia Minerals

The binary compounds Li2O.5Al2O3 and Li2O.Al2O3 can be formed easily by reaction of pure materials at 1500°C. The ternary compounds βeucryptite and βT-spodumene and solid solutions involving these two compounds can be prepared by reaction of Li2CO3, Al2O3, and SiO2 at 1300°C. The thermal expansions of the lithium aluminates are very high, but the expansions of β-spodumene and β-spodumene solid solutions are very low. The compound β-eucryptite is unusual in that it shows a high thermal contraction to 1000°C. Some relations between the expansion data and the crystal structure of the phases given above are discussed.