Effects of torsions on the integrated intensity of diffracted X-rays from silicon crystals

A very sensitive method to detect long-range strain in otherwise perfect crystalline material has been proposed [Saka (2003). J. Appl. Cryst. 36, 249-254]. In this method, the specimen was rotated around the scattering vector. By rotating the specimen, the integrated intensity of higher-order reflections was significantly increased from that in the initial vertical position. The results obtained were explained by assuming that the specimen was bent around an axis on the surface of the specimen, with the axis deviating slightly from the direction parallel to the edge of the specimen. In the present paper, it is shown that the results can be clearly explained by a model where the specimen is uniformly bent with a small torsion around the axes parallel to the specimen edges. The present model is highly probable, as the axes of the bending and torsion are parallel to the edges of the specimen.