Effect of Fe substitution on structural, magnetic and magnetocaloric properties of nanocrystalline La0.7Te0.3Mn1-xFexO3 (x=0.1, 0.3)

Structural, magnetic and magnetocaloric properties of the nanocrystalline La(0.7)Te(0.3)Mn(1-x)FexO(3) (x=0.1 and 0.3) perovskite manganites were investigated prepared by the sol-gel method. X-ray diffraction indicates that the samples crystallize in rhombohedral crystal structure with R (3) over barc space group for x=0.1 and orthorhombic structure with Pbnm space group for x=0.3. The average crystallite sizes were calculated using Debye Scherer's formula and were found to be similar to 31 nm and 26 nm for La0.7Te0.3Mn0.90Fe0.1O3 and La0.7Te0.3Mn0.7Fe0.3O3 samples, respectively. The scanning electron microscopy images confirm the homogeneity of the nanocrystalline samples. Temperature dependence magnetization measurements revealed a decrease of ferromagnetic-paramagnetic phase transition with increasing Fe-content. The Curie temperature (T-C) determined for x=0.1 and 0.3 are 171 K and 78 K, respectively. Based on the magnetic field dependence of magnetization, M(H), the magnetic entropy change broken vertical bar Delta S-M broken vertical bar of the samples were calculated. The maximum entropy change broken vertical bar Delta S-max broken vertical bar values are 1.17 Jkg(-1) K-1 for x=0.1 and 0.44 Jkg(-1) K-1 for x=0.3 for a field change of 2 T. The relative cooling power was found to be 80 JK(-1) and 49 JK(-1) for the La0.7Te0.3Mn0.90Fe0.1O3 and La0.7Te0.3Mn0.7Fe0.3O3 samples, which are comparable to other manganites. Tuning of TC with Fe substitution on Mn-site and moderate magnetic entropy change and RCP values, as well as high stability, enable La(0.7)Te(0.3)Mn(1-x)FexO(3) (x=0.1 and 0.3) nanocrystalline manganites to be a competitive candidate among the magnetic refrigeration materials for wide temperature ranges from room temperature down to 50 K.