Damped soft phonons and diffuse scattering in 40%Pb(Mg[sub 1/3]Nb[sub 2/3])O[sub 3]-60%PbTiO[sub 3]

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TypeArticle
Journal titlePhys. Rev. B
Physical Review B (Condensed Matter and Materials Physics)
Volume73
Issue6
Pages06410712; # of pages: 64096
Subjectlead compounds; neutron diffraction; phonons; relaxor ferroelectrics; soft modes; solid-state phase transformations; X-ray diffraction
AbstractUsing neutron elastic and inelastic scattering and high-energy x-ray diffraction, we present a comparison of 40% Pb(Mg1/3Nb2/3)O3-60% PbTiO3 (PMN-60PT) with pure Pb(Mg1/3Nb2/3)O3 (PMN) and PbTiO3 (PT). We measure the structural properties of PMN-60PT to be identical to pure PT, however, the lattice dynamics are exactly that previously found in relaxors PMN and Pb(Zn1/3Nb2/3)O3 (PZN). PMN-60PT displays a well-defined macroscopic structural transition from a cubic to tetragonal unit cell at 550 K. The diffuse scattering is shown to be weak indicating that the structural distortion is long-range in PMN-60PT and short-range polar correlations (polar nanoregions) are not present. Even though polar nanoregions are absent, the soft optic mode is short-lived for wave vectors near the zone center. Therefore PMN-60PT displays the same waterfall effect as prototypical relaxors PMN and PZN. We conclude that it is random fields resulting from the intrinsic chemical disorder which is the reason for the broad transverse optic mode observed in PMN and PMN-60PT near the zone center and not due to the formation of short-ranged polar correlations. Through our comparison of PMN, PMN-60PT, and pure PT, we interpret the dynamic and static properties of the PMN-xPT system in terms of a random field model in which the cubic anisotropy term dominates with increasing doping of PbTiO3.
Publication date
Linkhttp://link.aps.org/abstract/PRB/v73/e064107
AffiliationNational Research Council Canada; NRC Canadian Neutron Beam Centre
Peer reviewedNo
NPARC number12328815
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Record identifierb30edd1f-1d23-4d2f-a26e-10c88750593a
Record created2009-09-10
Record modified2016-05-09
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