  Neutron elastic diffuse scattering experiments performed on Pb(Zn1/3Nb2/3)O3
(PZN) and on its solid solution with PbTiO3(PT), known as PZN-xPT, with x=4.5%
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. 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 (> 40 K), due to stronger correlations between
the polar regions. Neutron inelastic scattering measurements have also been
performed on PZN-xPT. The results show the broadening of the transverse
acoustic (TA) phonon mode at a small momentum transfer q upon cooling. We
attribute this broadening to the appearance of the polar nanoregions.
