Investigation of structural magnetic and magnetocaloric properties of (La1-XPrX)0.85Ag0.15MnO3 (0.0 ≤ x ≤ 1.0 ) manganites

In this study, the structural, magnetic and magnetocaloric properties of the polycrystalline (La1-xPrx)0.85Ag0.15MnO3 (0.0 ≤ x ≤ 1.0 ) compounds, prepared by the sol-gel method, were investigated. The structural properties were studied by employing X ray Difraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) analyses. The XRD results have shown that samples produced for x ≤ 0.2 concentration values have crystallized in the rhombohedral structure. The samples, prepared for x ≥ 0.3 concentration values, have crystallized in the orthorhombic structure. SEM observations show that the particles are closely packed. By the increase of Pr concentration, the average particle size of each compound decreases. From the EDX analyses, the obtained concentration and the desired conteration values are close to each other. The magnetic properties were studied by employing magnetization versus temperature (M(T)) and magnetization versus magnetic field (M(H)) Analyses. From the results of M(T) and M(H) measurement all compounds show magnetic phase transition from paramagnetic to ferromagnetic phase by decreasing temperature. With the substituting of Pr for La, the Curie temperature, TC, decreases. Except for(La0.8Pr0.2)0.85Ag0.15MnO3 sample the magnetic entropy change values are decreased by the increase of Pr content. Furthermore relative cooling power (RCP) values first increased considerably for x = 0.1 and then slightly decreased by increase of Pr concentration. Arrot plots reveal second order magnetic phase transition for all samples. These properties make the compounds, produced for x < 0.4 concentration values, good candidates for the practical magnetic refrigeration.