Synthesis and Thermal Expansion of Lithium Trititanate with Ramsdellite Type Structure

A compound with an ideal formula, Li2Ti3O7, which had a ramsdellite type structure (hereinafter referred to as R phase) was synthesized by using the melt-quenching method and the solid-phase reaction method in the composition range of 72 to 76mol% TiO2 to confirm the effectiveness of the melt-quenching method. The composition range depended on the synthesis temperature. The R phase was confirmed to exist as a solid solution with the general formula expressed as LixTi4-x/4O8 (2.3≤x≤2.4 at 1150°C). The phase change of the R phase occurred as R->H (hexagonal phase)->Li4Ti5O12 (S phase)+TiO2 (rutile: r)->R with increasing temperature, and the H phase forming region previously reported in literature coincided with that of the R phase. Moreover, possibility of the existence of stoichiometric Li2Ti3O7 as a stable phase at room temperature was indicated.