Tuning the magnetocaloric and structural properties of La_0.67Sr_0.28Pr_0.05Mn_1–xCo_xO₃ refrigeration materials

Abstract The structural, magnetic and magnetocaloric properties of perovskite manganites La 0.67 Sr 0.28 Pr 0.05 Mn 1− x Co x O 3 ( x = 0.05, 0.075 and 0.10) (LSPMCO) are investigated. LSPMCO crystallizes as a rhombohedral structure with R -3 c space group. As the Co content increases, the cell volume expands, the Mn–O–Mn bond angle reduces and the length of the Mn–O bond increases. The samples show irregular submicron particles under a Zeiss scanning electron microscopy. The particle size becomes larger with increasing doping. The chemical composition of the samples is confirmed by x-ray photoelectron spectroscopy (XPS). The ferromagnetic (FM) to paramagnetic (PM) phase transition occurs near the Curie temperature ( T C ), and all transitions are second-order phase transitions (SMOPT) characterized by minimal thermal and magnetic hystereses. Critical behavior analysis indicates that the critical parameters of LSPMCO closely align with those predicted by the mean-field model. The T C declines with Co doping and reaches near room temperature (302 K) at x = 0.075. The maximum magnetic entropy change ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>−</mml:mo> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:msubsup> <mml:mi>S</mml:mi> <mml:mi mathvariant="normal">M</mml:mi> <mml:mrow> <mml:mi>max</mml:mi> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> ) at x = 0.05 is 4.27 J/kg⋅K, and the relative cooling power (RCP) peaks at 310.81 J/K. Therefore, the system holds significant potential for development as a magnetic refrigeration material, meriting further professional and objective evaluation.