Between the faces of twinned crystals there are often reentering angles, by which it is sometimes possible to determine the law of twinning. Incoming angles, as it has long been observed, contribute to the accelerated growth of the twin compared to the single crystal. However, in twinning, the incoming angles do not always occur. Sometimes the generalized faces of twinned individuals can be parallel to each other or form “exiting” angles ...
The study of the elementary dislocation mechanism of plastic flow of crystals can far from always give an answer to the question of macroscopic transformation of their external form, which is a consequence of the collective motion of dislocations ...
Knowledge of the orientation dependence of the effective impurity distribution coefficients KEf between solid and liquid phases during crystal growth from the melt is necessary for proper doping in order to obtain semiconductor crystals with given properties ...
ZnO zincite crystals are characterized by a point symmetry group 6 tt and a vorzite-type structure p63mc . Usually zincite crystals, obtained both from the gas phase and by hydrothermal method, have a prismatic-pyramidal habitus formed by faces (0001), (0001), (1010), (1011) ...
The practical significance of the crystallographic varieties of simple forms deduced by G. B. Bokii [1940] became evident after the derivation of the twin laws.
According to the law of formation of crystal dissolution bodies formulated by W. Goldschmidt and F. Wright [Goldschmidt, Wright. 1904], the angles and vertices on the dissolution body of a crystal correspond to the poles of the faces present during its growth; the edges to the zones of the faces. This law is cited by A. E. Fersman [1955] as a rule by which the forms of crystal growth should be distinguished from the forms of dissolution. In 1958, F. Frank showed that if the dissolution (growth) rate is a function only of the orientation of its surface, then during dissolution (growth) of a crystal, a point on the surface of a given orientation has a rectilinear trajectory directed perpendicular to the surface of the polar diagram of inverse dissolution (growth) rates of the crystal at the corresponding point.
The relation between plastic deformation of a crystal and mechanical impact is unambiguously established by means of symmetry.The shape of impact or pressure is the deformation at a point. The symmetry of a resting point, according to A. V. Shubnikov, is equal to ∞/∞ m, and the symmetry of a point moving in one direction is equal to ∞ m. The polar vector possesses such symmetry. The stress on the face produced by this vector can be equivalently described by a two-dimensional polar tensor with symmetry ∞ m.
Изучая научные труды В. И. Михеева, прежде всего поражаешься исключительной целеустремленностью и четкостью основной линии его творчества. Эта линия — прямое продолжение и развитие трудов его учителя А. К- Болдырева, а тем самым и трудов Е. С. Федорова. Вот почему в наших глазам В. И. Михеев является выдающимся представителем федоровской школы, кристаллографо-минералогической школы Горного института. Чтобы проследить определяющие иерты творческого пути В. И. Михеева, необходимо вспомнить некоторые характерные моменты из его биографии.
