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APS » Journals » Phys. Rev. Lett. » Volume 87 » Issue 21
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Phys. Rev. Lett. 87, 217601 (2001) [4 pages]

Evidence for Pb-O Covalency in Tetragonal PbTiO3

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Yoshihiro Kuroiwa*, Shinobu Aoyagi, and Akikatsu Sawada
Department of Physics, Okayama University, Okayama 700-8530, Japan

Jimpei Harada
X-ray Research Laboratory, Rigaku Corporation, Akishima, Tokyo 196-8666, Japan

Eiji Nishibori, Masaki Takata, and Makoto Sakata
Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan

Received 20 July 2001; published 6 November 2001

Accurate charge-density distributions of cubic and tetragonal PbTiO3 and BaTiO3 have been obtained by the MEM(maximum entropy method)/Rietveld analysis using synchrotron-radiation powder data. The Pb-O bonds in tetragonal PbTiO3 show rather strong covalency, while those in cubic PbTiO3 are ionic. This is the clear evidence of the Pb-O hybridization in tetragonal PbTiO3, which has been theoretically predicted as a key factor of much larger ferroelectricity of this substance than that of BaTiO3. Tetragonal PbTiO3 forms a layered structure of a two-dimensional covalent-bonding network consisting of the Ti-O5 pyramid.

© 2001 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.87.217601
DOI:
10.1103/PhysRevLett.87.217601
PACS:
77.84.Dy, 61.10.Nz

*To whom all correspondence and requests for materials should be addressed.Email address: kuroiwa@science.okayama-u.ac.jp

 
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