Improvement of magnetocaloric properties around room temperature in (1-x) La0.6Ca0.4MnO3/(x) La0.6Sr0.4MnO3 (0 ≤ x ≤ 1) composite system

In this research paper, a detailed investigation is conducted on the magnetocaloric effect (MCE) properties of the two phases (1-x) La0.6Ca0.4MnO3/(x) La0.6Sr0.4MnO3 composite system by experiments and numerical calculations. The polycrystalline manganites La0.6Ca0.4MnO3 and La0.6Sr0.4MnO3 are synthesized by the citric-gel method. Rietveld refinements of the X-ray diffraction patterns show that both samples are single phase. The Curie temperature T-c is found to be 255 and 365 K for La0.6Ca0.4MnO3 and La0.6Sr0.4MnO3, respectively. The study of the temperature dependence of the magnetic entropy change of (1-x)La0.6Ca0.4MnO3/(x)La0.6Sr0.4MnO3 composite indicates that the optimum composition stands for x = 0.6. Indeed, it gives comparable contributions of two parent compounds, leading to a practically uniform variation of entropy over a wide temperature range. The theoretical modeling of the MCE using Landau theory reveals an acceptable concordance with experimental data indicating the importance of magnetoelastic coupling and electron interaction in the MCE properties of manganite systems.