Synthesis and properties of La_{1 – x}Sr_xNiO₃ and La_1–xSr_xNiO₂

Abstract

Superconductivity has been realized in films of La 1− x Sr x NiO 2 . Here we report synthesis and characterization of polycrystalline samples of La 1− x Sr x NiO 3 and La 1− x Sr x NiO 2 (0 ≤ x ≤ 0.2). Magnetization and resistivity measurements reveal that La 1− x Sr x NiO 3 are paramagnetic metal and La 1− x Sr x NiO 2 exhibit an insulating behavior. Superconductivity is not detected in bulk samples of La 1− x Sr x NiO 2 . The absence of superconductivity in bulk La 1− x Sr x NiO 2 may be due to the generation of hydroxide during reduction, a small amount of nickel impurity, or incomplete reduction of apical oxygen. The effect of interface in films of La 1− x Sr x NiO 2 may also play a role for superconductivity.