Role of nickel doping on magnetocaloric properties of La0.7Sr0.3Mn1−xNixO3 manganites

Abstract

This study reports the effect of Ni substitution for Mn on structural, magnetic, and magnetocaloric properties of La0.7Sr0.3MnO3 manganite synthesized by sol–gel technique. The structural, morphological, and magnetic properties are investigated using x-ray diffractometer (XRD), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM) systems. XRD results showed that all samples crystallize in rhombohedral structure. Thermomagnetic measurements showed that TC decreases with the addition of Ni from 363 K for x = 0.00 to 324 K for x = 0.06. ΔSM determined by Maxwell’s relations and Landau theory gave compatible results in the transition temperature and region above. ΔSMmax values were determined as 4.52, 4.51, 4.41, and 3.90 J kg−1 K−1 for x = 0.00, 0.02, 0.04, and 0.06 at 5T, respectively. The Arrott plots and the scaling analysis of ΔSM, which collapsed on a single curve, showed that magnetic transitions are of second order.