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Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/544

Title: Raman spectra and structural phase transition in nanocrystalline lead lanthanum titanate
Authors: Zhou, Qifa
Chan, Helen L. W.
Zhang, Qingqi
Choy, Chung-loong
Subjects: Lead compounds
Lanthanum compounds
Raman spectra
Particle size
Heat treatment
Ferroelectric materials
Crystallites
Nanostructured materials
Grain size
Sol-gel processing
X-ray diffraction
Phonon spectra
Ferroelectric transitions
Issue Date: 15-Jun-2001
Publisher: American Institute of Physics
Citation: Journal of applied physics, 15 June 2001, v. 89, no. 12, p. 8121-8126.
Abstract: The effects of particle size on the structure and Raman spectra of lead lanthanum titanate nanocrystalline particles are investigated. Samples with different particle sizes were prepared by the sol-gel process using different calcination temperatures. The sizes of the crystallites of particles were determined by x-ray diffraction with the aid of Scherrer's equation. Raman vibration modes of samples with various particle sizes were also studied by Raman scattering at room temperature. The results show that the tetragonal distortion of the unit cell apparently decreases with decreasing particle size: the soft A₁(1TO) phonon mode which is related to the spontaneous polarization of ferroelectric materials shifts toward lower frequency, and other peaks exhibit broadening and intensity changes with decreasing particle size. These are attributed to a phase transformation from the ferroelectric tetragonal to the paraelectric cubic phase. The above phenomena are related to a grain size-induced structural phase transition.
Rights: © 2001 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Q.F. Zhou et al., J. Appl. Phys. 89, 8121 (2001) and may be found at http://link.aip.org/link/?jap/89/8121
Type: Journal/Magazine Article
URI: http://hdl.handle.net/10397/544
ISSN: 00218979
Appears in Collections:MRC Journal/Magazine Articles
AP Journal/Magazine Articles

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