Thermal-diffuse scattering of x rays by phasons

Abstract
The absolute intensity of thermal-diffuse phason scattering, surrounding a charge-density-wave (CDW) satellite in reciprocal space, is derived both for a monatomic crystal and for a compound. Since the phason frequency approaches zero near an incommensurate CDW satellite, phason scattering dominates other diffuse scattering and can be used to measure phason velocities. The theory is applied to the layered compound 1T-TaS2.