Investigation of Magnetic Entropy Change and Griffiths-like Phase in La0.65Ca0.35MnO3 Nanocrystalline
In this paper, we reported a detailed study of magnetic properties and magnetic entropy change of La 0.65Ca0.35MnO3 nanocrystalline, which was prepared by using the sol–gel method. The structural analysis shows that the nanocrystalline sample crystalizes in orthorhombic perovskite structure and the average size is about 30 nm. Based on the measurements of magnetization, a larger effective magnetic moment was obtained and an obvious deviation of the inverse magnetic susceptibility was observed, indicating the presence of Griffiths-like phase in paramagnetic region. Around the temperature of paramagnetic–ferromagnetic phase transition, the magnetocaloric effect (as represented by the magnetic entropy change) was determined from isothermal magnetization and calculated with Maxwell relation. Compared with bulk polycrystalline, the obtained magnetic entropy change in nanocrystalline is small. This result clearly reveals that the decrease of the sample’s size to nanoscale is detrimental for the increase of magnetocaloric effect of magnetic materials. Besides the particle size and surface effect, the paramagnetic–ferromagnetic phase transition driven from first to second order should be a main reason for the small magnetocaloric effect in La 0.65Ca0.35MnO3 nanocrystalline.
KeywordsManganite Magnetocaloric effect Nanocrystalline Phase transitions
This work was supported by the National Nature Science Foundation of China (grant nos. 11004196, 11204131, 11204270, and U1332140).
- 18.Phan, M.H., Peng, H.X., Yu, S.C.: J. Appl. Phys. 97, 10M306 (2005)Google Scholar