Abstract
The effect of strontium doping on the structural, magnetic and magnetocaloric properties of La0.67Ca0.33-xSrxMn0.98Fe0.02O3 samples for (x = 0.15; 0.2.and 0.3) has been investigated. Analysis using X-ray diffraction shows there is an orthorhombic structure with Pnma space group symmetry for x = 0.15 compound, whereas there is a rhombohedral structure exhibiting R3‾c space group symmetry found for x = 0.2, and x = 0.3 compounds. A second-order magnetic phase transition from ferromagnetic to paramagnetic state transition is evidenced for all samples, with Curie temperature (TC) values equal to 329 K, 330 K and 350 K and that respectively for x = 0.15, 0.2 and 0.3. Based on isothermal magnetization measurements versus applied magnetic field at several temperatures around TC, the magnetic entropy change was calculated, which is very close to that approximated by the Landau theory for.x = 0.15. Under an applied magnetic field of 5 T, one can see the maximum magnetic entropy change (−ΔSMmax) values, which are around 4.89, 4.71 and 3.35 J.kg− 1.K−1 for x = 0.15, 0.2, and 0.3 respectively. It confirms that close to room temperature, these manganites are admirably potential functional materials, which can be applied as solid state magnetic refrigerants.
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