Effect of high-energy ball milling on the magnetocaloric properties of La_0.7Ca_0.2Sr_0.1MnO₃

We report an experimental–theoretical analysis of the large magnetocaloric effect observed in the compound La_0.7Ca_0.2Sr_0.1MnO₃, synthesized by high-energy ball milling assisted by heat treatment. We demonstrated that this method induces crystal structure distortions and defects, which are responsible for the excellent MC properties. X-ray diffraction and Rietveld refinement allowed quantification of the high levels of microstrain and distortion of the synthesized orthorhombic structure (Pnma). Temperature-dependent magnetization measurements reveal a Curie temperature of approximately 310 K; furthermore, a large value of magnetic entropy change |ΔSM|= 4.11 Jkg⁻¹ K⁻¹ and relative cooling power of 61.12 Jkg⁻¹ were estimated by means of Maxwell's equations under an applied field (H) of 18 kOe, making this manganite a promising material for refrigeration applications. Electron paramagnetic resonance spectra of the doped manganite show the presence of Mn⁴⁺ ions, which strengthen the double-exchange interaction (ferromagnetic). It is demonstrated that the high-energy ball milling process assisted by heat treatment is an easy, economic, and fast method for synthesizing doped manganites, showing improved magnetocaloric properties compared to those of the same material synthesized by other methods.