### Session B20: Focus Session: Properties of Ferroelectrics and Relaxors

11:15 AM–2:15 PM, Monday, March 5, 2007

Chair: Hans Christen, Oak Ridge National Laboratory

Abstract ID: BAPS.2007.MAR.B20.7

### Abstract: B20.00007 : Phonon anomalies induced by polar nano-regions in a relaxor ferroelectric

12:51 PM–1:03 PM

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#### Authors:

Guangyong Xu
(Brookhaven National Laboratory)

Jinsheng Wen
(Brookhaven National Lab/Stonybrook University)

Chris Stock
(Johns Hopkins University)

Peter Gehring
(National Institute of Standards and Technology)

Inelastic neutron scattering was used to measure both acoustic and optic phonons polarized along (110) (T2 mode) in the relaxor ferroelectric compound PZN-4.5PT. In the low temperature rhombohedral phase, a single domain state was achieved by cooling the single crystal sample under an external electric field of 2 kV/cm along the [111] direction. Phonon measurements were performed near the (2,2,0) and (2,-2,0) Bragg peaks. We have found that the TA2 phonon couples closely to the diffuse scattering, which arises from polar nano-regions in the system. With the redistribution of diffuse scattering under the external field (see Ref. 1), a clear hardening of TA2 mode was observed near the (2,2,0) Bragg peak, while the TA2 mode near (2,-2,0) Bragg peak softens significantly and becomes over-damped. Our results indicate local inhomogeneities such as the PNR can have direct and significant effects on the lattice dynamics and stability of the whole system. Ref. 1: Electric-field-induced redistribution of polar nano-regions in a relaxor ferroelectric'', Guangyong~Xu, Z.~Zhong, Y.~Bing, Z.-G.~Ye, and G.~Shirane, Nature Materials 5, 134, (2006).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.MAR.B20.7