Magnetic, magnetocaloric and thermoelectric properties of nickel doped manganites

In this study, we investigate structural, magnetic, magnetocaloric and thermoelectric properties of La0.7Sr0.3Mn1-xNixO3 compounds with 0.025 ≤ x ≤ 0.125. X-ray diffraction analysis shows the structure transformation from the R-3c rhombohedral to the Pbnm orthorhombic structure with Ni2+ doping at x ≥ 0.075 composites. The dc thermal magnetization measurements reveal the monotonic decrease in both Curie temperature and magnetization values with Ni2+ addition. The change in magnetic properties of the studied system is correlated to the ferromagnetism suppression and the antiferromagnetism promotion according to some cooperative intrinsic and extrinsic factors. Results show that Ni2+ addition affects the magnetocaloric properties, where it shifts the maximum value of the magnetic entropy change towards lower temperatures with relative cooling power of 88, 105, 47 J/kg for x = 0.025, 0.075 and 0.125 composites, respectively. Moreover, it is observed that Ni2+ doping increases the absolute value of Seebeck coefficient and decreases hole conduction interval.