Exploring the environmental potential of LS⌷MO-SG: critical behavior and magnetocaloric effect for green cooling technologies

Abstract

This study investigated La0.67Sr0.3⌷0.03MnO3 (LS⌷MO-SG), an A-site deficient perovskite manganite synthesized by sol-gel method. X-rays Diffraction (XRD) confirmed the formation of a single-phase rhombohedral structure with the space group R3c. Crystallite size analysis (Scherrer, Williamson-Hall, Halder-Wagner) yielded an average size of 18 nm, while scanning electron microscopy (SEM) revealed an average grain size of 45 nm, indicating excellent structural uniformity at the nanoscale. The nanometric scale significantly enhances magnetocaloric properties through increased surface domain density and improved magnetic exchange interactions, crucial for performance improvement. Magnetization measurements yielded a Curie temperature of 360 K. Analysis using modified Arrott plots, the Kouvel-Fisher method, and magnetocaloric effect (MCE) data determined critical exponents β, γ and δ consistent with mean-field theory, providing insights into magnetic interactions. Magnetocaloric analysis revealed a significant magnetic entropy change (ΔSM) of 3.6 J/kg.K and a high relative cooling power (RCP) of 253 J/kg under a 5 T magnetic field, highlighting the high potential of the material for magnetic refrigeration applications. The study was further complemented by modeling based on Landau theory and the Hamad approach, providing a deeper understanding of the relationship between critical phenomena and the magnetocaloric effect. The strong agreement between experimental results and mean-field theory, combined with the high magnetic entropy and RCP values, positions LS⌷MO-SG as a promising material for more efficient and environmentally friendly magnetic refrigeration.