X-Ray Diffraction Studies of the Structures of Dynamically Compressed Be, Al, LiF, KCI, and SiO2

Results from an X-ray diffraction structural study of crystals under shock-wave compression are presented. An analysis of the date leads to the conclusion that at the shock front, the crystals undergo universal structural changes over the entire range of pressures studied. X-ray diffraction patterns suggest that the relaxation process of structural change is related to a change in the state of the crystal electron subsystem responsible for the chemical bonding in substance. The process of structural change at shock front can be divided into two stages: 1) uniaxial compression of the structure, the compression direction coincides with the direction of shock-wave propagation; 2) transformation of the unstable, uniaxially compressed, initial structure to a structure determined by the degree (depth) of relaxation of the electron subsystem responsible for the chemical binding of the ionic component of the crystal. X-ray diffraction patterns of a number of crystals at both stages of the process of structural change are presented.