Neutron elastic diffuse scattering experiments performed on $\mathrm{Pb}\left({\mathrm{Zn}}_{1/3}{\mathrm{Nb}}_{2/3}\right){\mathrm{O}}_3$ (PZN) and on its solid solution with ${\mathrm{PbTiO}}_3\left(\mathrm{PT}\right),$ known as PZN-$x\mathrm{PT},$ with $x=4.5\mathrm{}$ and 9 % around many reflections show that diffuse scattering is observed around reflections with mixed indices in the transverse and diagonal directions only. From the width of the diffuse scattering peak a correlation length is extracted. In PZN, we have reported that the diffuse scattering is more extended in the transverse than in the diagonal directions [D. La-Orauttapong, J. Toulouse, J. L. Robertson, and Z.-G. Ye, Phys. Rev. B 64, 212101 (2001)]. In the present work, the results show that the addition of PT leads to a broadening of the diffuse scattering along the diagonal, relative to the transverse directions, indicating a change in the orientation of the polar regions. Also, with the addition of PT, the polar nanoregions condense at a higher temperature above the transition than in pure PZN $(>\mathrm{}40\mathrm{}\mathrm{K}),$ due to stronger correlations between the polar regions. Neutron inelastic scattering measurements have also been performed on PZN-$x\mathrm{PT}.$ The results show the broadening of the transverse acoustic phonon mode at a small momentum transfer q upon cooling. We attribute this broadening to the appearance of the polar nanoregions.

• Received 18 September 2002

DOI:https://doi.org/10.1103/PhysRevB.67.134110