EQUATIONS FOR DIFFUSE-SCATTERING FROM PSEUDOBINARY SPHALERITE F(4)OVER-BAR-3M SYSTEMS

The equations describing X-ray diffuse scattering in crystals with the pseudobinary sphalerite F43mBAR structure (e.g. Hg1-xCdxTe and other pseudobinary semiconductors) are presented accurately up to the second order in local atomic displacements. This treatment considers the loc al properties from the noncentrosymmetric structure as well as complex scattering factors. The result contains additional terms related to t he noncentrosymmetric crystal properties and the imaginary parts of th e atomic scattering factors. Expressions are also presented that are a pplicable to an experiment involving difference anomalous dispersion t echniques. Equations relating the various terms at symmetry-related po ints in reciprocal space are included as well as the least-squares met hod required to solve the matrix equations from diffraction data taken in a volume of reciprocal space.