College Park, Maryland      June 6 - 10 , 2004

M3-C6 (3:00 PM): Structure of Nano-Polar Domains in Ferroelectric KTa1-xNbxO3

G. Yong (Lafayette College), R. Erwin (NIST Center for Neutron Research), O. Svitelskiy (Lehigh University), L. A. Boatner (Oak Ridge National Laboratory), B. Hennion (Laboratoire Léon Brillouin, C.E.A Saclay, 91191 Gif-sur-Yvette Cedex), J. Toulouse (Lehigh University), S. M. Shapiro (Brookhaven National Laboratory)

The temperature-dependent diffuse neutron scattering (DS) associated with the cubic-to-tetragonal (CT) transition in single crystals of ferroelectric KTa1-xNbxO3 (KTN) has been characterized for x = 0.16 and 0.19. The features of the DS are similar to those found in relaxor-ferroelectric transitions. The DS is consistent with domain wall crossings in a direction perpindicular to the domain polarization. The DS intensity and measureable domain size are maximal near the temperature where macroscopic strains and relief of extinction appear. The measured DS does not overlap the inelastic scattering from soft optic phonons. An accomodation of the sublattice strain across domain walls is able to bring the observed and calculated DS structure factors into agreement.

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