Study of solid-state synthesized Pr0.55Sr0.45Mn1−xCrxO3 perovskites with x = 0.0, 0.05, 0.1 and 0.15: Rietveld analysis and magnetic and magnetocaloric properties for magnetic refrigeration applications

Abstract

In the current study, the structural (X-ray diffraction (XRD)), magnetic, critical behavior and magnetocaloric properties of polycrystalline Pr_0.55Sr_0.45Mn_1−xCr_xO₃ manganite samples (with x = 0.0, 0.05, 0.1 and 0.15) were investigated. All our samples were prepared from the stoichiometric powder mixtures of binary oxides via solid-state reactions at high temperatures. The compounds crystallized in an orthorhombic structure with the Pnma space group, according to the Rietveld refinement of the XRD pattern. All the samples exhibited a second-order FM-to-PM phase transition, according to the temperature and field-dependent magnetization measurements; however, the Curie temperature (T_C) value decreased from 300 K to 275 K, as the Cr (% x) content increased from 0.00 to 0.15. Using Maxwell thermodynamic relations, the magnetocaloric effect (MCE) in terms of maximum entropy change (−ΔS^max_M) and relative cooling power (RCP) was calculated with isothermal magnetization data around T_C. In a magnetic field shift of 5 T, the highest values of the magnetic entropy change (−ΔS^max_M) were determined to be 3.8 J kg⁻¹ K⁻¹, 3.63 J kg⁻¹ K⁻¹, 3.87 J kg⁻¹ K⁻¹, and 2.55 J kg⁻¹ K⁻¹ for x = 0.0, x = 0.05, x = 0.1, and x = 0.15, respectively. For x = 0.0, x = 0.05, x = 0.1, and x = 0.15 at 5 T, the highest value of the relative cooling power RCP was found to be 247 J kg⁻¹, 254.1 J kg⁻¹, 205.1 J kg⁻¹, and 201 J kg⁻¹, respectively. The RCP value of 254.1 J kg⁻¹ (5% of chromium) was equivalent to 58% of the RCP value of gadolinium metal. Technically, the developed material is highly promising for magnetic refrigeration because of these significant values.