کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5492124 | 1525138 | 2017 | 6 صفحه PDF | دانلود رایگان |
Structural, magnetic and magnetocaloric properties of the nanocrystalline La0.7Te0.3Mn1âxFexO3 (x=0.1 and 0.3) perovskite manganites were investigated prepared by the sol-gel method. X-ray diffraction indicates that the samples crystallize in rhombohedral crystal structure with R3Ì c space group for x=0.1 and orthorhombic structure with Pbnm space group for x=0.3. The average crystallite sizes were calculated using Debye Scherer's formula and were found to be ~31Â nm and 26Â nm for La0.7Te0.3Mn0.90Fe0.1O3 and La0.7Te0.3Mn0.7Fe0.3O3 samples, respectively. The scanning electron microscopy images confirm the homogeneity of the nanocrystalline samples. Temperature dependence magnetization measurements revealed a decrease of ferromagnetic-paramagnetic phase transition with increasing Fe-content. The Curie temperature (TC) determined for x=0.1 and 0.3 are 171Â K and 78Â K, respectively. Based on the magnetic field dependence of magnetization, M(H), the magnetic entropy change |ÎSM| of the samples were calculated. The maximum entropy change |ÎSmax| values are 1.17Â Jkgâ1Â Kâ1 for x=0.1 and 0.44Â Jkgâ1Â Kâ1 for x=0.3 for a field change of 2Â T. The relative cooling power was found to be 80Â JKâ1 and 49Â JKâ1 for the La0.7Te0.3Mn0.90Fe0.1O3 and La0.7Te0.3Mn0.7Fe0.3O3 samples, which are comparable to other manganites. Tuning of TC with Fe substitution on Mn-site and moderate magnetic entropy change and RCP values, as well as high stability, enable La0.7Te0.3Mn1âxFexO3 (x=0.1 and 0.3) nanocrystalline manganites to be a competitive candidate among the magnetic refrigeration materials for wide temperature ranges from room temperature down to 50Â K.
Journal: Physica B: Condensed Matter - Volume 511, 15 April 2017, Pages 83-88