Synthesis and properties of La1 – x Sr x NiO3 and La1–x Sr x NiO2

Abstract

Superconductivity has been realized in films of La1−x Sr x NiO2. Here we report synthesis and characterization of polycrystalline samples of La1−x Sr x NiO3 and La1−x Sr x NiO2 (0 ≤ x ≤ 0.2). Magnetization and resistivity measurements reveal that La1−x Sr x NiO3 are paramagnetic metal and La1−x Sr x NiO2 exhibit an insulating behavior. Superconductivity is not detected in bulk samples of La1−x Sr x NiO2. The absence of superconductivity in bulk La1−x Sr x NiO2 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 La1−x Sr x NiO2 may also play a role for superconductivity.