Dy-Doped La_0.51Sr_0.49MnO₃ nanoparticles: Tuning structural and magnetocaloric properties via Sol-Gel synthesis for energy-efficient applications

We report the structural and magnetic properties of sol-gel-synthesized Dy-doped La_0.51Sr_0.49MnO₃ nanoparticles, which average ≈ 27–29 nm in size. The chemical composition was confirmed using energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The magnetization behavior of the samples showed clear evidence of a transition from ferromagnetic to paramagnetic states in all three cooling and warming processes: Zero Field-Cooled Warming, Field-Cooled Cooling, and Field-Cooled Warming. The Curie temperature exhibits a drop as the concentration of Dy³⁺ increases, from 372 K to 317 K. Approximately 95 % of the average refrigerant Gd material under 5T is found in the relative cooling power values of the La_0.51Sr_0.49MnO₃ sample, which range from 62 to 387 J/kg when the applied magnetic field is changed from 1T to 5T. In maintaining with the mean-field theory, the critical exponents were determined to be (β = 0.541 and γ = 0.991 for Dy0.00), (β = 0.559 and γ = 0.954 for Dy0.045), and (β = 0.570 and γ = 1.103 for Dy0.09). Dysprosium doping does not alter the universality class, indicating that the material's fundamental behavior remains unaffected. This nanomaterial has a reasonably strong magnetocaloric response and is inexpensive, making it a possible material for active magnetic refrigerators.