RESEARCH BREACHES OF FLUORITE STRUCTURE BY DOUBLE CRYSTAL X-RAY TOPOGRAPHY AND HIGH RESOLUTION DIFFRACTOMETRY

Grigory Kablis1, Vasily Punegov2, Anatoly Petrakov2

154, Pervomayskaya St., 167610, Syktyvkar, Russia, e-mail cryst@geo.komi.ru
2Address*: Physics Faculty, 55, Octyabrskiy Av., 167000, Syktyvkar, Russia

Keywords: x-ray topography, diffraction, fluorite

Last years interest to the development of high resolution methods of x-ray topography and diffractometry [1,2] has greatly increased. In contrast to traditional X-ray structural analysis these methods allow to receive essentially new information about structural features of crystals. As a rule, all natural monocrystals have a mosaic structure. In a number of cases in such objects the space change of structural properties (non-homogeneous distribution of defects, elastic deformations of a crystalline lattice, impurities etc.) is possible.

The methods of high resolution two and three-crystalline diffractometry, and also double crystal topography are very sensitive to the distortions of crystalline structure. With the help of these methods it is possible to determine the type of defect, it's size and concentration, and also depth of bedding of separate large defect.

In this work the monocristals of fluorite were investigated. Double crystal X-ray topography were conducted in Bragg case on Cu Ka1 - radiation. The almost perfect crystal of silicon, set in symmetrical reflected position, was used as a crystal-monochromator. The resolution was of the order 10 microns, that allowed to observe defects on depth of several tens micron.

X-ray diffractometry measurements were conducted by two and three-crystalline diffractometer. Given angular distributions of intensity have allowed to reveal characteristic structural features of monocrystals of fluorite. Widths of the diffraction maxima testified about mosaic structure of researched crystals.

1. X-ray topography and high resolution diffraction/ 2nd European Symposium. Berlin, Germany, 5-7 September 1994. 215 p
2. X-ray topography and high resolution diffraction/ 3rd European Symposium. Palermo, Italy, 22-24 April 1996. 219 ð.