XXVIII. The Influence of crystal size on the absorption factor as applied to Debye-Scherrer diffraction patterns

Abstract

The absorption factor derived by the methods of Claassen and Bradley for a cylindrical crystal is applied to the case of a spherical crystal, for which a set of absorption factor tables is constructed. It is then shown that the absorption factor A for a cylindrical powder specimen consists of two parts, a micro-absorption factor t corresponding to the individual reflecting crystallites which are assumed to be spherical, and a, the macro-absorption factor for the specimen as a whole. The effects of crystallite aggregation, size and dilution upon A are discussed. Each constituent in a mechanical mixture must be given its own absorption factor on account of the different values of the micro-absorption factors which can only be neglected when the dimensions of the crystallites fall below 10^-5 cm. The influence of the micro-absorption factor on the evaluation of the amplitude of atomic vibration is also briefly discussed.