Structural study and large magnetocaloric entropy change at room temperature of La1−x□xMnO3 compounds |
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Authors: | C. Henchiri T. Mnasri A. Benali R. Hamdi E. Dhahri M. A. Valente B. F. O. Costa |
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Affiliation: | Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, Université de Sfax, B. P. 802, Sfax 3018 Tunisia ; Research Unit UPIM, Faculty of Science, University of Gafsa, 2112 Tunisia ; I3N, Physics Department, University of Aveiro, 3810-193 Aveiro Portugal ; College of Health and Life Sciences, Hamad Bin Khalifa University, Doha Qatar ; CFisUC, Physics Department, University of Coimbra, RuaLarga, 3004-516 Coimbra Portugal |
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Abstract: | In this study, our central focus is to investigate the magnetocaloric characteristics of a La1−x□xMnO3 (x = 0.1, 0.2 and 0.3) series prepared by a sol–gel technique published in Prog. Mater. Sci., 93, 2018, 112–232. The crystallographic study revealed that our compounds crystallize in a rhombohedral structure with Rc. Ferromagnetic (FM) and paramagnetic (PM) characters were detected from the variation in magnetization as a function of magnetic fields at different temperatures. The second order transition was verified from the Arrott plots (M2vs. (μ0H/M)), where the slopes have a positive value. In order to verify the second order, we traced the variation of magnetization vs. temperature at different magnetic fields for x = 0.2. This revealed a ferromagnetic (FM)–paramagnetic (PM) transition when temperature increases. Relying on the indirect method while using the Maxwell formula, we determined the variation in the entropy (−ΔSM) as a function of temperature for different magnetic fields for the three samples. We note that all the studied systems stand as good candidates for magnetic refrigeration with relative cooling power (RCP) values of around 131.4, 83.38 and 57.26 J kg−1 with magnetic fields below 2 T, respectively. Subsequently, the magnetocaloric effect was investigated by a phenomenological model for x = 0.2. The extracted data confirm that this phenomenological model is appropriate for the prediction of magnetocaloric properties. The study also demonstrated that this La0.8□0.2MnO3 system exhibits a universal behaviour.In this study, our central focus is to investigate the magnetocaloric characteristics of a La1−x□xMnO3 (x = 0.1, 0.2 and 0.3) series prepared by a sol–gel technique. |
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