The effect of strontium deficiency in Pr0.6Sr0.4MnO3 perovskite manganites

The structural, magnetic and magnetocaloric properties of the mixed valent manganites Pr0.6Sr0.4−x□xMnO3 (0 ≤ x ≤ 0.2) with perovskite structure have been investigated. X-ray diffraction (XRD) analysis using Rietveld refinement show that all our samples are single phase and crystallize in the orthorhombic structure with Pbnm space group. Strontium vacancy leads to a gradual increase of the unit cell volume. Paramagnetic (PM) to ferromagnetic (FM) transitions have been observed in all our synthesized samples. With increasing Sr-deficient amount, the Curie temperature TC decreases from 310 K for x = 0 to 170 K for x = 0.2. From the measured magnetization data of Pr0.6Sr0.4−x□xMnO3 (0 ≤ x ≤ 0.2) samples as a function of magnetic applied field, the associated magnetic entropy change ΔSM close to the Curie temperature TC has been determined. The Pr0.6Sr0.35□0.05MnO3 compound (x = 0.05) exhibits a maximum entropy change ΔSMMax of 4.81 J/(kg K) at 260 K in a magnetic applied field of 5 T. ΔSMMax decreases to 4.17 J kg/K at 175 K for x = 0.2 in the same field magnitude. Large relative cooling power (RCP) value of 260.7 J/kg is obtained for x = 0.05 sample at a field change of 5 T.

Research highlights
► The strontium-deficient Pr0.6Sr0.4−x□xMnO3 powder samples were synthesized using the solid state reaction at high temperature. All our samples are single phase and crystallize in the orthorhombic structure with Pbnm space group. The unit cell volume increases with Sr-deficient amount. All our compounds are ferromagnetic at low temperatures with a Curie temperature TC decreasing with deficiency amount. A large magnetocaloric effect is observed in our samples with RCP value of 260.7 J/kg upon a magnetic applied field change of 5 T for x = 0.05 sample making our compounds potential candidates for magnetic refrigeration.