Particle size effects on La0.7Ca0.3MnO3.pdf

ARTICLE IN PRESS Journal of Magnetism and Magnetic Materials 322 (2010) 2360–2368Contents lists available at ScienceDirectJournal of Magnetism and Magnetic Materials0304-88 doi:10.1 n Corr Solid St of China E-mjournal homepage: /locate/jmmmParticle size effects on La0.7Ca0.3MnO3: size-induced changes of magnetic phase transition order and magnetocaloric studyWei Tang a, Wenjian Lu a,c,n, Xuan Luo a, Bosen Wang a, Xuebin Zhu a, Wenhai Song a, Zhaorong Yang a, Yuping Sun a,b,n a Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People’s Republic of China b High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People’s Republic of China c Center for Strongly Correlated Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Koreaa r t i c l e i n f o Article history: Received 6 December 2009 Received in revised form 12 February 2010 Available online 20 February 2010 Keywords: Particle size Magnetocaloric Nanoparticle53/$ - see front matter 2010 Elsevier B.V. A 016/j.jmmm.2010.02.038 esponding authors at: Key Laboratory of M ate Physics, Chinese Academy of Sciences, He . Tel.: +0086 551 559 2757; fax: +0086 551 ail addresses: wjlu@ (W.J. Lu), ypsuna b s t r a c t The structure, magnetic properties, and magnetocaloric effect of La0.7Ca0.3MnO3 ceramics with different particle sizes have been investigated. It is found that the Curie temperature increases first, and then decreases as particle size decreases and the type of magnetic phase transition changes from first-order to second-order, which may be attributed to surface pressure effects. The maximum magnetic entropy change DSmaxM and relative cooling power (RCP) show non-monotonic behaviors with decreasing the particle size. However, for the 3400 nm sample, the magnetic entropy change DSM reaches the maximum values of 6.41 and 8.63 J/kg K for the field changes of 2.0 and 4.5 T, r