Size effect on the crystal structure of barium titanate nanoparticles

被引：0

作者：

Yashima, Masatomo ^{[1
]}

Hoshina, Takuya ^{[2
]}

Ishimura, Daiju ^{[1
]}

Kobayashi, Syuuhei ^{[1
]}

Nakamura, Wataru ^{[1
]}

Tsurumi, Takaaki ^{[2
]}

Wada, Satoshi ^{[2
]}

机构：

[1] Department of Materials Science and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan

[2] Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan

来源：

Journal of Applied Physics | 2005年 / 98卷 / 01期

关键词：

Barium compounds - Crystal structure - Neutrons - Particle size analysis - Perovskite - Polycrystalline materials - Raman scattering - Single crystals;

D O I：

暂无

中图分类号：

学科分类号：

摘要：

A size effect on crystal structure has been investigated for barium titanate (BaTiO3) nanoparticles of 40-, 140-, and 430-nm sizes, by means of neutron and high-resolution synchrotron x-ray powder-diffraction and Raman-scattering techniques. These samples were prepared by a modified two-step thermal decomposition method from barium titanyl oxalate, resulting in very few lattice impurities. Rietveld analysis of the neutron-diffraction data for the 430-nm- and 140-nm-sized BaTiO3 particles was performed assuming a single phase of tetragonal (P4mm) structure. The axial ratio ca of tetragonal BaTiO3 decreases with a decrease in particle size from 430 to 140 nm. Barium titanate particles with a size of 40 nm consist of (1) tetragonal crystals (83 wt %) with a large cell volume and an axial ratio of unity ca=1.000 (5) and of (2) a hexagonal phase (P 63 mmc, 17 wt %) with a large unit-cell volume. Rietveld and maximum-entropy method analyses suggest that there exist atomic displacements from the ideal site of a cubic structure and a spontaneous polarization of the tetragonal phase even in the 40-nm-sized BaTiO3 particles. The nuclear-density distribution of the 140-nm-sized particles with a high dielectric constant does not exhibit a large positional disorder, while the Ba atom of tetragonal BaTiO3 in the 40-nm-sized particles has a smaller atomic displacement parameter. © 2005 American Institute of Physics.

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