3-D mapping of diffuse scattering in PZN-xPT

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High energy (67 keV) x-ray diffuse scattering measurements were performed on single crystals of Pb(Zn₁/₃Nb₂/₃)O₃-xPbTiO₃ (PZN-xPT). A novel technique was developed to map out the diffuse scattering distribution in all three dimensions around a large number of Bragg peaks simultaneously, taking advantage of the almost flat Ewald sphere of the high energy x-ray beam. For x=0, 4.5%, and 8%, the results are very similar, indicating same type of correlations of polarizations in these compounds. Our results show that the diffuse scattering intensity consists of six <110> rod-type intensities around reciprocal lattice points. These rod-type intensities are very likely due to condensations of soft optic phonon modes, polarized in the perpendicular <110> directions. A simple model is suggested where these soft phonon modes condense into static {110} type planar or ``pancake'' shaped correlations of the in-plane <110> polarizations.