Optimizing Magnetocaloric Properties in Rare-Earth Doped La0.8Sr0.2MnO3 Ceramics: Unveiling the Synergy of Lattice Distortion and Electronic Structure

Perovskite manganites stand out as one of the most promising candidate materials for ceramics and room-temperature magnetic refrigeration due to their inherent advantages: excellent chemical stability, low manufacturing cost, straightforward synthesis process, and minimal eddy current losses. However, the broader development and application of these materials in room-temperature magnetic refrigeration have been hampered by their relatively low magnetocaloric properties (MCP) near room temperature. To address this limitation, this study focuses on La 0.8 Sr 0.2 MnO 3 ceramics (LSMO) as a representative perovskite manganite. We systematically enhanced its Curie temperature (Tc) and MCP through A-site rare-earth (RE) ion doping and investigated the doping effects on its MCP and the underlying mechanisms. Key findings reveal that while gradient doping with different RE ions preserved the parent crystal structure, it significantly altered Mn-O bond lengths/angles, unit cell parameters, and the degree of MnO 6 octahedral distortion. Experimental results demonstrate that as the RE ion doping concentration increased, the Tc of La 0.8- x RE x Sr 0.2 MnO 3 ceramics progressively approached room temperature and the magnetic entropy change exhibited a declining trend, yet consistently remained higher than that of the undoped LSMO ceramics. Compared to the undoped LSMO ceramics, A-site RE ion doping effectively tunes the Tc to the vicinity of room temperature and simultaneously enhances the overall MCP. Employing a combined strategy of chemical synthesis and theoretical calculations, we elucidated the “crystal-electronic coupling” mechanism. This mechanism reveals how the synergistic effect of “MnO 6 octahedral lattice distortion” and “ d -orbital electronic structure modulation” governs changes in Tc and MCP. This study's rare-earth A-site doping strategy and “crystal-electronic coupling” mechanism deliver actionable experimental evidence and theoretical frameworks for advancing room-temperature magnetocaloric materials research.