Vol 74 Iss. 2

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 ...

Distorted crystal forms, as repeatedly noted in the literature, are peculiar indicators of the symmetry of the crystal-forming medium. They include forms with reduced symmetry, (but compared to the true symmetry of a given crystalline substance), which are combinations of parts of the true prossive forms in the form of aggregates of faces connected by elements of the external (visible) symmetry of the crystal ...

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 ...

Due to the fact that the processes of oriented crystallization find more and more widespread application in various fields of science and technology, the issues of epitaxial growth of crystals cause increased interest of scientists and practitioners ...

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 ...

The mineralogical museum of LMI received a spectacular sample of germanium, which was the upper part of a large crystal grown from the melt by the pulling method, the device for realization of which is shown in Fig....

The practical value of rock crystal deposits is largely determined by the quality of crystals, which depends to a large extent on the development of various kinds of defects in them. Analysis of the quality of raw materials is necessary at all stages of industrial development of deposits: from prospecting to exploitation and exploration ...

Physicochemical conditions of mineral formation in natural conditions rarely remain constant, experiencing gradual or pulsagaon changes, which is reflected in the zonal and vectorial structure of individuals ...

In the industrial production of semiconductor silicon, the external shape of single crystals has received much attention. It has been found that directly in the process of growing from the melt by some features of the shape of mocco crystals one can get an idea of their internal structure, including the dislocation structure .....

This paper presents the results of investigations of the structure of the upper (in the range of 0-250 m) horizons of the Antarctic ice column from the area located 50 km south of Mirny station. The material of the study was an ice core with a diameter of 180 mm obtained from a vertical borehole ...

The study of the character and nature of crystal-optical orientation in the glacial cover is a very labor-intensive but extremely important task. This is due to the fact that the spatial position of the main axes of grains reflects the deeply hidden internal characteristics of the city, most closely related to the peculiarities of the formation of the ice sheet as a whole

When considering the conditions of crystal nests formation, the question of the dynamics of mineral-forming solutions constantly arises. Repeatedly suggested the stagnant state of solutions inside the nests, which led some researchers to the conclusion about the development of crystal formation processes in the regressive stage of metamorphism in the conditions of a closed physical and chemical system ...

The peculiarities of crystal formation are directly reflected in the development of internal defects in them, present in all real crystals and determining their quality. Quality is the main, and at present the only reliable criterion for assessing the suitability of the applied modes of growth, so the establishment of the relationship between the growth renin and the conditions of defect formation is an important task for practice

The names of simple crystallographic forms, proposed in 1924 on the initiative of Prof. A.K.Boldyrev by Fedorov Institute, have been widely spread and recognized. This is evidenced by the statement of famous foreign crystallographers I.D.H. Donnaya and H. Kurien, who spoke at the Committee on Nomenclature of the French Mineralogical and Crystallographic Society in 1958: “The principles on which a satisfactory terminology of forms should be based are known. We owe this mainly to Grote and the crystallographers of the Fedorovsky Institute <...>. The nomenclature described here is used with some minor variations in the languages: German, English, Spanish, Italian, Dutch, Russian” ....

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) ...