Size-dependent magnetocaloric effect in GdVO4 nanoparticles
Ruan, M. Y. 1Yang, C. Q. 1Wang, L. 2Jin, P. B. 3Guo, Z. L. 1Wei, X. L. 1Wu, W. X.1
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作者信息
1. Northwest Normal Univ
2. Huazhong Univ Sci & Technol
3. Xi An Jiao Tong Univ
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Abstract
We investigated the magnetization and electron spin resonance (ESR) in nanocrystals of antiferromagnet GdVO4 with the grain size ranging from 30 nm to 5 mu m. Our nanoparticles with an average size reduction from 5 pm to 300 nm exhibited enhanced paramagnetic-like behavior, in which the weakly coupled spins can be well aligned along the direction of an external magnetic field, resulting in a giant entropy change of -Delta S-M = 45 J/kg K at 3 K for Delta H = 7 T. Moreover, with a further reduction of grain size to similar to 30 nm, the saturation magnetization together with the negative entropy change -Delta S-M,S- max decreased dramatically. The aggregation effect is believed to be responsible for the decline in -Delta S-M,S- max in which small nanoparticles agglomerating to 'large' grains made them behave like bulk material. Finding the critical point of positive size effect on magnetocaloric effect offered a new way to achieve large magnetic entropy change. (C) 2021 Elsevier B.V. All rights reserved.
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Elsevier