InternationalMathematical, physical and chemical tablesTables for Crystallography Volume C Edited by E. Prince © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. C, ch. 7.4, p. 657
## Section 7.4.2.4. Correction factor for powders B. T. M. Willis
^{d} |

Thermal diffuse scattering in X-ray powder-diffraction patterns produces a non-uniform background that peaks sharply at the positions of the Bragg reflections, as in the single-crystal case (see Fig. 7.4.2.4).
For a given value of the scattering vector, the one-phonon TDS is contributed by all those wavevectors **q** joining the reciprocal-lattice point and any point on the surface of a sphere of radius with its centre at the origin of reciprocal space. These **q** vectors reach the boundary of the Brillouin zone and are not restricted to those in the neighbourhood of the reciprocal-lattice point. To calculate α properly, we require a knowledge, therefore, of the lattice dynamics of the crystal and not just its elastic properties. This is one reason why relatively little progress has been made in calculating the X-ray correction factor for powders.

### References

Suortti, P. (1980*a*).

*Powder TDS and multiple scattering. Accuracy in powder diffraction*, edited by S. Block & C. R. Hubbard, pp. 8–12.

*Natl Bur. Stand. (US) Spec. Publ.*No. 567.