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Quartz iiionocrystals have a wide application in science and technology (SHUBNIKOV; CADY) : in applied optics, radioengineering, supersonics, etc. These crystals have a particularly important significance owing to their piezoelectric properties. For a more efficient utilization of quartz crystals and for expanding the field of their application in the future, it is necessary to examine in more detail the imperfection of these crystals caused by the action of various physical factors, since the physical properties of crystals depend largely upon the degree of perfection of their structure. Consequently, the study of the imperfection of crystals is one of the urgent problem of the solid state physics. Among the various methods for the study of the defects, the radiographic methods are of a particular importance.
The X-ray diffraction patterns obtained from quartz crystals are, however, very complicated, and it is not always possible t o interpret them unambiguously hence, to discover the true structural imperfections produced by various factors.
The present work was developed during the investigation of the effects of the dynaniic scattering of X-ray waves in quartz crystals depending on the applied electric field. The object was to investigate the influence of the constant field on the Borrinann effect, the fringe effect, the energy flow, the pendular bands arising in nionocrystal samples (YAMASHITA, KATO ; ADAMIAN et al. 1979 ; BORRMANN), the displacement bands, the moir6 patterns produced in twin-block interferometers (AUTIIIER et al. ; BEZLR-GANIAN; AVETISSIAN; BEZIRGANIAN, ASLANIAN), as well as on the interference patterns obtained in three-block interferometers.
During the examination of this problem we ran into difficulties which provided grounds for thoughts about the peculiarities of the diffraction (scattering) of X-rays in imperfect (mosaic) crystals in general and in quartz crystals in particular. For a reliable determination of the characteristic features of the diffraction of X-rays in quartz crystals we investigated the scattering of X-rays in separate crystals and in systems composed of two or three crystals (twin-block and three-block interferomet em).