Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5447324 | Journal of Physics and Chemistry of Solids | 2017 | 34 Pages |
Abstract
The crystal and electronic structures and the magnetic and magnetocaloric properties of off-stoichiometric LaMnO3 nanoparticles (NPs) with various particle sizes DÂ =Â 20-100Â nm were studied. The Rietveld refinement revealed that all NPs were crystallized in the rhombohedral structure, with varied structural parameters dependent on D. Magnetization (M) measurements indicated a considerable difference between zero-field-cooled and field-cooled magnetizations at temperatures below ferromagnetic-paramagnetic (FM-PM) phase transition, particularly for the samples with DÂ =Â 25-40Â nm. These results are ascribed to spin-glass-like behaviors and magnetic inhomogeneity. We also found the possibility of tuning the FM-PM phase transition temperature (TC) from 77 to 262Â K, which is dependent on both D and W (the eg-electron bandwidth). Under an applied field of HÂ =Â 50Â kOe, the absolute maximum magnetic entropy change that achieved around TC can be improved from 4.02Â JÂ kgâ1Â Kâ1 for DÂ =Â 40Â nm to 6.36Â Jâ
kgâ1â
Kâ1 for DÂ =Â 100Â nm, corresponding to the relative-cooling-power values of 241-245Â Jâ
kgâ1. We also analyzed the data of M and magnetic entropy change based on theoretical models to further understand the magnetic property and phase-transition type of the NP samples.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
P.S. Tola, H.S. Kim, D.H. Kim, T.L. Phan, J.S. Rhyee, W.H. Shon, D.S. Yang, D.H. Manh, B.W. Lee,