Diffuse scattering anisotropy and inhomogeneous lattice deformations in the lead magnoniobate relaxor PMN above the Burns temperature

Neutron diffuse scattering measurements on single crystal PbMg sub(1/3)Nb sub(2/3)O sub(3) above the Burns temperature are reported. The high temperature elastic diffuse component is highly asymmetric near reciprocal lattice points not corresponding to high-symmetry directions. This asymmetry can be described using Huang scattering formalism assuming that the scattering originates from mesoscopic lattice deformations due to elastic defects. Qualitative agreement between this model and the experimental data is achieved with simple, isotropic defects. It is demonstrated that the weak satellite maxima near Bragg reflections can be interpreted in terms of a finite resolution effect.