Extinction in single crystals of UO₂

he measurements of nuclear neutron diffraction intensities for a single crystal of UO₂ by Faber & Lander [Phys. Rev. B. (1976), 14, 1151-1164] have been reanalysed using both the Cooper-Rouse and Becker-Coppens extinction formalisms. The results indicate that this crystal is type I in nature, not type II as was suggested by Faber & Lander, and this conclusion is essentially the same as that obtained for a different single crystal of UO₂ used in our earlier study of the wavelength dependence of extinction in this material [Sakata, Cooper, Rouse & Willis (1978). Acta Cryst. A34, 336-3411. The analysis of the Faber & Lander data gave a value for the scattering-length ratio b_U/b_O = 1.448 (2).