Analysis of magnetic and structural phase transition behaviors of La 1− xSr xCrO 3 for preparation of phase diagram

Abstract

The phase transition behavior of perovskite-type compounds, La 1− x Sr x CrO 3, was investigated by differential scanning calorimetry (DSC), dilatometry, dc magnetic susceptibility measurement and X-ray diffraction analysis. Both second-order magnetic phase transition from antiferromagnetic to paramagnetic and first-order structural phase transition from orthorhombic to rhombohedral were observed in the DSC or dilatometric curve of every specimen. The temperatures of both these magnetic and structural phase transitions decreased linearly with an increase in Sr content. The structural phase transition temperature of La 1− x Sr x CrO 3 with x less than 0.11 is higher than the magnetic phase transition temperature; however, a larger decrease in structural phase transition temperature than in magnetic phase transition temperature was observed with an increase in Sr content, resulting in a structural phase transition temperature lower than the magnetic phase transition temperature for La 1− x Sr x CrO 3 with x of more than 0.12. It was also observed that the heat of absorption of the structural phase transition decreased with an increase in x. In the dependence of dc magnetic susceptibility on temperature, variations by not only magnetic but also structural phase transitions were observed. It was also revealed that thermal expansion coefficient is affected not only by structural phase transition but also magnetic phase transition. Magnetic and structural phase diagram of La 1− x Sr x CrO 3, suggesting the existence of two Sr contents and temperatures at which triple phases coexist, was proposed.