A New X-Ray Diffraction Method for Studying Imperfections of Crystal Structure in Polycrystalline Specimens

Abstract

A new double spectrometer method for the study of polycrystalline materials is developed. From intensity data of the diffracted spots and known angular settings of the specimen, the angular range of reflection of the misaligned scattering regions in a crystallite is determined statistically. The instrument and the technique of the multiple exposure method is described. The statistical evaluation of the data is discussed and a mathematical treatment introducing correction terms as functions of the azimuth and of the Bragg angle is presented. A commercial silicon powder specimen was investigated. The average angular range of reflection was found to be nearly the same for all (hkl)‐reflections with exception of (111), (333), and (444). The study of broadening effects with the same instrument has been started. The new double spectrometer method for polycrystalline specimens described in this paper is based on the examination of numerous microscopic spots reflected by individual crystallites. The small spots on the diagram facilitate the detection and measurement of small broadening effects. Independently, the pattern of angular misalignment of the same reflecting crystallite can be accurately determined. For both broadening and misalignment, the method offers statistical information which is representative of the specimen and which can be compared for different (hkl)‐reflections. The total information on imperfections obtained in this manner may serve to correlate experimental observation with the theory of dislocations and hence, may be useful in the understanding of structure‐sensitive properties of solids.