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Nb polarization in Ferroelectric Perovskites KNbO3 and (PbZn1/3Nb2/3O3)0.88-(PbTiO3)0.12

Published online by Cambridge University Press:  01 February 2011

E. Mamontov
Affiliation:
Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104-6272, U. S. A.
W. Dmowski
Affiliation:
Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104-6272, U. S. A.
T. Egami
Affiliation:
Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104-6272, U. S. A.
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Abstract

XANES measurements have demonstrated that Nb polarization in (PbZn1/3Nb2/3O3)0.88-(PbTiO3)0.12 is small compared to that in KNbO3. This finding disproves the view of Nb5+ as invariably ferroelectrically active cation, and demonstrates that its polarizability depends on the Asite cations. Our results do not support conventional view of relaxor behavior in Pb(B'1/3Nb2/3)O3 ferroelectrics as a consequence of disruption of the connectivity of polarizable Nb5+ ions by their non-polarizable B' counterparts. Instead, they speak in favor of scenario in which relaxor behavior is caused by randomness of the local direction of Pb polarization due to chemical disorder on the B-sites of the perovskite structure.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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