期刊
SOLID STATE COMMUNICATIONS
卷 129, 期 7, 页码 479-483出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ssc.2003.10.029
关键词
nanostructures; chemical synthesis; crystal structure and symmetry; phase transitions
We report a novel, low temperature (450-600degreesC) route for the synthesis of highly crystalline and homogeneous nanoparticles of lanthanum calcium manganese oxide La0.67Ca0.33MnO3 (LCMO). The nanocrystallites, with average particle size of 30 nm, possess a ferromagnetic-paramagnetic transition temperature (T-c) of 300 K, which is about 50 K higher than that of a bulk single crystal. The transition temperature was found to be inversely proportional to the particle size. The Rietveld analysis of the powder X-ray diffraction data of the phase-pure nanopowders reveals that the particle size reduction leads to a significant contraction of the unit cell volume and a reduction of the unit cell anisotropy. We propose that these two lattice effects are responsible for the observed enhancement in T-c. (C) 2003 Elsevier Ltd. All rights reserved.
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