Diffuse x-ray scattering from weakly metamict zircon

Diffuse x-ray (Cu K alpha(1)) scattering from alpha-decay radiation-damaged natural zircon has been investigated at room temperature. Huang scattering around Bragg reflections was observed in samples with radiation doses between 0.06 and 2 x 10(18) alpha-decay events g(-1), but none in a highly crystalline natural zircon sample (<0.01 x 10(18) alpha-decay events g(-1)). Huang scattering (similar to q(-2)) dominates for small wavevectors, while Stokes-Wilson scattering (similar to q(-4)) is observed at larger values of q from the Bragg reflection. The displacement field produced by alpha-decay radiation damage is shown to correspond to transverse shear waves. The unit-cell expansion observed in zircon is thus interpreted as originating as a consequence of the shear waves propagating in the crystal, rather than from simply longitudinal expansion waves. A cluster size between 70 and 140 Angstrom, depending on the degree of damage, characterizes the defect accumulation.