L.G. Kariev, J.A. Kochergina, O.A. Mexichev, V.A. Feodorov, D.V. Manukhina

In the work the physical model reflecting behavior of an ionic crystal in electric field at simultaneous heating, allowing in particular is presented. It allows to investigate processes of moving and formation of own point defects, as charge carriers, and their accumulation in surface regions of a crystal. In the model interaction between separate ions and the point defects, caused coulomb's potential is considered. As a basis a crystal lattice NaCl is taken. In the model dependence of amplitude of oscillations of ions in points of the lattice from temperature is considered at an assumption that frequency of fluctuations is a constant. For calculations the certain volume of a crystal in the form of sphere that allowed to define values of the intensity in the point from internal areas of a crystal without recalculation over of intensity from each ion was set. Energy distribution of ions in volume of a crystal for variously charged surfaces is received. In percentage of the total number of ions from temperature and quantity of considered planes dependences of quantity of vacancies are found in the model. In dependences sites on which the quantity of defects tends to saturation that correlates with experiment are pointed. Modeling has allowed to get an insight into distinctions of a structural condition of surfaces of crystals with various polarity. So for positively charged surface surplus of positive interstitial ions of the metal was observed. The surface charged negatively, lacks positive ions lattice points (spillover of vacancies). In the last case infringement stoichiometry of structure leads to the earlier electric breakdown in comparison with a surface charged positively that proved by the experiment. Occurrence is connected with infringement stoichiometric structure on surfaces of crystals of a new phase in the form of spheroidal formations in an amorphous condition. By the X-ray analysis the increase in interatomic distance in subsurface crystal that can be connected with presence in them of congestions of point defects is shown.