International
Tables for
Crystallography
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

International Tables for Crystallography (2006). Vol. C, ch. 7.4, p. 657

Section 7.4.2.4. Correction factor for powders

B. T. M. Willisd

7.4.2.4. Correction factor for powders

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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[link]). 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 [2\sin\theta/\lambda] 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.

[Figure 7.4.2.4]

Figure 7.4.2.4 | top | pdf |

One-phonon scattering calculated for polycrystalline nickel of lattice constant a (after Suortti, 1980a[link]).

References

Suortti, P. (1980a). 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.








































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