Microstructure and Magnetic Properties of La-Ca-Sr-Mn-O Perovskite Ceramics

Abstract

A wide range of di erent types of materials, from metals to ceramics, exhibit the magnetocaloric e ect [1]. Generally, the magnetocaloric e ect manifests itself as a reversible increase in temperature when the magnetic material is placed in a magnetic eld, and the maximum magnetocaloric e ect occurs near the Curie temperature. Magnetic ceramics materials are very stable at room temperature, can be compositionally tuned to adjust the Curie temperature, and do not corrode in water. This makes them an attractive option for use as regenerators for magnetic refrigeration systems. Families of functional materials with a large magnetocaloric e ect have been found in several perovskite type manganese oxides such as Caand Sr-doped lanthanum manganites, La0.67Ca0.33−xSrxMnO3 (x = 0; 0.33) [2]. These samples show a substantial magnetocaloric e ect in a temperature range around their respective Curie temperature, which makes the compounds suitable for air-conditioning and refrigeration applications. By varying the composition parameter x the Curie temperature can be adjusted between 267 K (x = 0) and 369 K (x = 0.33) [2]. In this contribution, the structure, microstructure and the in uence of high pressure oxygenation on magnetisation behaviour of La0.67Ca0.33−xSrxMnO3, prepared by solid state synthesis were investigated.