Magnetic properties and magnetocaloric effect in La1.4-x Ce (x) Ca1.6Mn2O7 perovskites synthesized by sol-gel method

Abstract

The magnetic properties and magnetocaloric effect near the critical phase transition temperatures of La1.4-x Ce (x) Ca1.6Mn2O7 (x = 0, 0.2) double layered manganites are analyzed. Polycrystalline nanopowders of La1.4Ca1.6Mn2O7 and La(1.2)Ce(0.2)Ca(1.6)Mn2O(7) were successfully synthesized by a sol-gel method. The magnetic measurements suggest an antiferromagnetic alignment of the Ce and Mn moments in La1.2Ce0.2Ca1.6Mn2O7. Both Ce3+ and Ce4+ ions are present in the doped sample, as indicated by the XPS spectra. A moderate magnetocaloric effect was found for both samples, with the maximum entropy change located at temperatures near the magnetic transition ones. The high RCP(S) values together with the broadened magnetic entropy curves suggest the possibility to use these materials for magnetic refrigeration devices.