GB1246410A - Improvements in methods and apparatus for the topography of crystals - Google Patents

Abstract

1,246,410. X-ray diffraction apparatus. COMPAGNIE FRANCAISE THOMSON HOUSTON-HOTCHKISS BRANDT. 17 Jan., 1969 [19 Jan., 1968], No. 2947/69. Heading H5B. In a method of X-ray crystallography which permits the ready detection of stacking faultse.g. mosaic structure-in a crystal E, the beam from the linear focus F 1 of an X-ray tube is passed through the vertical and horizontal slots F 2 and F 3 to provide a planar diverging beam D of angle α incident upon the crystal, which is arranged, by rotations 1 and 2 about perpendicular axes, such that a given set of (hkl) planes is vertical and, at some point of the irradiated surface, satisfies the Bragg condition. The crystal is then rotated or oscillated at uniform speed through an angle limited to that which is necessary to ensure that all the planes of the set over the whole irradiated surface successively satisfy the Bragg condition, whereby missing or misdirected planes give rise to clear regions in the otherwise substantially uniformly blackened band recorded on the stationary photographic film P. In the apparatus of Fig. 2, a diverging beam from the horizontal slot F 2 -of 10 to 30 microns height-is incident on the specimen E, which is rotatable about a horizontal axis by a worm and pinion, and is mounted on a base 8 rotatable to and fro at constant speed about a vertical axis by mechanism 9, a counter in tube 11 permitting initial adjustment of the specimen to a suitable position with the pivotally mounted film 10 in a raised position. The film 10 may alternatively be mounted in front of the specimen, to receive reflected rays.