2D modeling of regeneration surface growth on a single-crystal sphere
- PDF / 970,283 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 81 Downloads / 166 Views
TAL GROWTH
2D Modeling of Regeneration Surface Growth on a Single-Crystal Sphere V. G. Thomasa, P. N. Gavryushkina,b, and D. A. Fursenkoa a Institute
of Mineralogy and Petrography, Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090 Russia b Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090 Russia e-mail: [email protected] Received May 26, 2014
Abstract—This paper investigates the evolution of a sphere produced from a single crystal potassium alum in course of its regeneration, using numerical 2D-simulation in the kinematic model, which describes the growth of the regenerating surfaces.The modeling results demonstrate a qualitative agreement between the predictions of the kinematic model and real processes of sphere regeneration. It is shown that the face arising on the regenerating surface of a sphere may grow either more slowly or more rapidly than the surrounding surface. In the latter case, the face interacts with the regeneration surface and disappears from the sphere surface before intersecting in edges with neighboring faces. The influence of the input model parameters on the numerical modeling results is analyzed. It is established that the roughness parameters of the initial surface of a single-crystal sphere significantly affect the surface evolution during regeneration. DOI: 10.1134/S1063774515030219
INTRODUCTION The mechanism of crystal regeneration and the phenomena observed during this process have attracted the attention of crystallographers and experts in crystal growth for more than 100 years. Despite the evident progress in the studies in this field (the state of affairs by the beginning of the 1980s was described in detail in [1]), a number of issues of key importance have not been considered yet. Therefore, more recently several studies have attempted to address these issues. Specifically, in [2] the process of crystal regeneration has been described using fractal analysis; and [3, 4] have developed a kinematic model aimed at capturing these processes. One unclear point is the evolution of the surface of a single-crystal sphere during growth. It is well known [5] that, when a single-crystal sphere is placed in a supersaturated solution, flat rounded areas corresponding to possible faces arise very rapidly on the sphere surface. These areas are surrounded by a macroscopically rough surface (Fig. 1a) composed of a large number of small pyramids or steps. During regeneration, these flat areas grow tangentially, up to the complete absorption of the macroscopically rough surface, intersection in edges, and transformation into polyhedron faces. At the same time, at the very beginning of regeneration of a sphere, one can observe flat areas on its surface which disappear after some time before their
intersection with neighbors (compare Figs. 1a and 1b). Their disappearance is caused by the absorption of the rough surface. These areas are characterized by relatively small Miller indices; their sizes and the instants of formation and subsequent d
Data Loading...
