Room-temperature structure, magnetic, and magnetocaloric properties of La0.8Sr0.2MnO3 ceramics by Ni-doped analyzed with first-principles calculations

This paper systematically investigates the influence of Ni 2+ doping on the structural, morphological, and magnetocaloric properties of La 0.8 Sr 0.2 Mn 1-x Ni x O 3 (x = 0.05, 0.10, 0.15) ceramics using the sol-gel method and first-principles calculations. First-principles calculations reveal that Ni 2+ doping alters the electronic structure and magnetic properties of the material, by altering the hybridization degree between the O-2p and Ni-3d orbitals, this change enhances the antiferromagnetic superexchange interactions and weakening the ferromagnetic double exchange interactions. The single-phase rhombohedral perovskite structure (R-3c space group (No.167)) of the material was confirmed by X-Ray Diffraction (XRD) and Transmission electron microscope (TEM). Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses further verify the successful incorporation of Ni 2+ into the material, with elliptical particle morphology and uniform elemental distribution with no evidence of elemental segregation. Magnetic Property Measurement System (MPMS) measurements reveal significant changes in the magnetic entropy change (ΔS M ) and relative cooling power (RCP) of La 0.8 Sr 0.2 Mn 1-x Ni x O 3 ceramics due to B-site Ni 2+ doping. At a doping level of x = 0.05, the material exhibits a maximum magnetic entropy change of 4.02 J/(kg·K) under an applied magnetic field of 5 T, with a Curie temperature (Tc) close to room temperature (Tc = 294 K). This paper provides theoretical references and experimental evidence for the structural and magnetocaloric modifications in perovskite manganites induced by B-site doping.