Synthesis of la_1-xM_xTiO₃ (M = Na, K; 0≤x≤ 0.4) and the electrical properties

Polycrystalline materials of La_1-xM_xTiO₃(M = Na, K;0≤x≤0.4) were prepared by solid-state reactions under an Ar atmosphere and their electrical properties were investigated as possible candidates for superconducting oxides. XRD analysis showed that the formation of orthorhombic perovskite-type compounds were obtained when × = 0 (LaTi_O3) and that pseudo-cubic or cubic phases were obtained when ϗ ≥ 0.1. The lattice constants of the products decreased when × increased, suggesting the formation of solid solutions. There were small deficiencies of the alkali metals. The products in both systems showed semiconductor to metal transitions as temperature decreased when x≥0.1, and striking decreases of resistivity around 25 K were observed in both systems.