Thermal Expansion Properties of Some Synthetic Lithia Minerals

The binary compounds Li 2 O.5Al 2 O 3 and Li 2 O.Al 2 O 3 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 Li 2 CO 3 , Al 2 O 3 , and SiO 2 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.