Effect of A-site ionic disorder on structure, magnetic and magnetocaloric properties of La_0.85-xNd_xAg_0.15-yK_yMnO₃ manganites

In this paper, the effect of A-site ionic disorder (sigma(2)) on the structure, magnetic and magnetocaloric properties in La0.85-xNdxAg0.15-yKyMnO3 have been investigated. X-ray diffraction analysis using Rietveld refinement shows that the crystal structure of the perovskite manganites changes from rhombohedral (space group R3 (C) over bar) to orthorhombic (space group Pnma) structure with the increasing in sigma(2). Magnetization measurements showed that, upon increasing sigma(2), ferromagnetic double exchange interaction of the perovskite manganites diminishes, and as a result, Curie temperature (T-C) of the samples decrease linearly. The inverse of susceptibility shows a downturn with decreasing temperature before T-C indicating the existence of the Griffiths phase for La0.62Nd0.23-Ag-0.K-099(0).051MnO3 (sigma(2) = 0.004). The magnetic phase transitions of all the samples are belongs to second order transition.