Abstract
Two-dimensional single-crystal synchrotron x-ray diffraction of the high-temperature plastic phase of reveals relatively sharp sheets of diffuse intensity (where represents the set of average structure allowed Bragg reflections). This intense and highly structured diffuse scattering arises from the large amplitude excitation of transverse polarized displacive modes of distortion and shows that a set of six possible orientations of the individual molecules in the plastic phase are strongly coupled with displacive relaxational degrees of freedom. Using Monte Carlo simulations to model the diffuse intensity, the displacive relaxations are shown to be along the molecular nearest-neighbor real space directions associated with the relative orientations of individual and nearest-neighbor tetrahedra.
4 More- Received 22 August 2007
DOI:https://doi.org/10.1103/PhysRevB.77.144205
©2008 American Physical Society