Structure evolution and dielectric behavior of polystyrene-capped barium titanate nanoparticles

H. Z. Guo, Ya Mudryk, M. I. Ahmad, X. C. Pang, L. Zhao, M. Akinc, V. K. Pecharsky, N. Bowler, Z. Q. Lin, X. Tan

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Polystyrene-capped barium titanate (BaTiO 3) nanoparticles with sizes of 11 nm and 27 nm were prepared using amphiphilic star-like diblock copolymer templates. The crystal structure evolution of these nanoparticles over a wide temperature range (10-428 K) was investigated by powder X-ray diffraction. The Rietveld refinement indicates that the abrupt structural transitions observed in micron-sized powders become broad as the particle size is reduced to a few tens of nanometers. The orthorhombic phase (Amm2) is observed in the range of 10-388 K, coexisting with the rhombohedral phase (R3c) at lower temperatures and with the tetragonal phase (P4mm) at higher temperatures. At room temperature (300 K), polystyrene-capped BaTiO 3 nanoparticles, both 11 and 27 nm sizes, primarily adopt the tetragonal phase, transforming to the cubic phase (Pm3m) at 398 K during heating. The phase evolution of the nanoparticles correlates well with their dielectric behavior. With the Landauer-Bruggeman effective approximation, the dielectric properties at room temperature of the BaTiO 3 core were calculated and the results are in agreement with the size effect of BaTiO 3 nanocrystals.

Original languageEnglish
Pages (from-to)23944-23951
Number of pages8
JournalJournal of Materials Chemistry
Issue number45
StatePublished - 7 Dec 2012


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