Dielectric Huang scattering from point defects in ionic crystals

Abstract

We discuss the intensity of the scattering of X-rays or neutrons from point defects in ionic crystals. It is well known that the long-range elastic distortion field surrounding a defect causes the intensity to diverge as the scattering wave-vector approaches a reciprocal lattice vector, an effect known as Huang scattering. We show that the dielectric polarization field surrounding a defect with a net charge in an ionic crystal gives rise to a divergence of the same kind and we derive a formula for the intensity, which includes this dielectric contribution. Published experimental analyses of Huang scattering in ionic crystals have not taken account of this contribution, and may need to be reconsidered.