La 1− x Sr x MnO 3 (0.33 ≤ x ≤ 1.0) Perovskites; A Powder Diffraction and Magnetisation Study

Abstract

Powders of strontium doped lanthanum manganates (LSM) with a nominal composition La 1 m x Sr x MnO 3 (0.33 h x h 1.0) were prepared by a solid-state reaction. The samples were characterised by x-ray powder diffraction (XRPD), neutron powder diffraction (NPD), and magnetisation measurements performed with a SQUID magnetometer. NPD patterns were further studied with Rietveld analysis. XRPD, NPD and Rietveld analyses show that samples with x up to 0.45 crystallise single phase in a rhombohedral unit cell in space group R-3c (#167). The composition x = 0.55 is best described with a tetragonal unit cell with unit cell parameters a = 3.846 A and c = 3.876 A. From x = 0.60 to x = 0.950 the samples are mixtures of LaMnO 3 and SrMnO 3 phases. Pure SrMnO 3 as well as the composition where x = 0.975 crystallise in hexagonal space group P63/mmc (#194). The bulk resistivity of the as prepared samples shows that increasing strontium content results in higher resistivity in the material.