Structural, magnetic and magnetocaloric properties in La0.67(Sr1−xMgx)0.33MnO3 (x = 0, 0.1, 0.3) compounds
Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials, Anhui University of Technology, Ministry of Education, 243002, Ma’anshan, China
2 Ma’anshan Shuntai Rare Earth New Materials Co., Ltd., 243100, Ma’anshan, China
3 School of Material Science and Engineering, Anhui University of Technology, 243002, Ma’anshan, China
4 School of Materials and Chemical Engineering, Anhui Jianzhu University, 230601, Hefei, China
Accepted: 21 November 2022
Published online: 12 December 2022
The La0.67(Sr1−xMgx)0.33MnO3 (x = 0, 0.1, 0.3) manganites have been prepared by sol–gel method, and the effect of Mg doping on their structure, magnetic and magnetocaloric properties has been researched. All the samples are crystallized in perovskite rhombohedral structure with space group . The slight increases in the edge length a and the cell volume with Mg doping indicates the replacement of Mg in Mn-site. The corresponding change of structure parameters, such as Mn–O bond length and Mn–O–Mn bond angle, weakens the exchange coupling between Mn3+ and Mn4+ and results in the decrease in the Curie temperature (TC). With increasing content of Mg, the local inhomogeneity and Griffiths-like phase evolve and induce the deviation of critical exponents from the mean-field model. The existence of these short-range ferromagnetic clusters broadens the temperature range of magnetic transition process, then depresses the magnetic entropy change (|ΔSM|) and flattens the |ΔSM|-T curve. The La0.67(Sr0.7Mg0.3)0.33MnO3 possesses a table-like magnetocaloric effect near room temperature (|ΔSM| is nearly constant of 0.51 ± 0.01 J kg−1 K−1 for field change of 1 T in the temperature range of 277 ~ 302 K), which is beneficial for the Ericsson cycle magnetic refrigerator.
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