Shaped crystal growth

R. O. Gmbel, ed.. Metallurgy of Elemental and Compound Semiconductors, Interscience Pubhshers, New York, 1961. Discusses eady work on semiconductor dendrites and other methods of growing shaped crystals. The special issue of / Cyst. Growth (Sept. 1980) is devoted to shaped crystal growth. 

Crystal Growth from Melts and Solutions 17.2.4.1. Growth from Melts 17.2.4.1.7. Shaped Crystal Growth. 

N. V. Abrosimov, V. N. Kurlov, and S. N. Rossolenko, 2003, Automated control of Czochralski and shaped crystal growth processes using weighing techniques . Prog. Cryst. Growth Charact. 46, 1-57. 

The observed Avrarrri exponent n values imply that the growth of crystals is more of a 2-dimensional disk shaped crystal growth rather than a spherical crystal growth. 

Figure 4.6 The growth of disk-shaped crystals, (a) All crystals have been nucleated simultaneously. All crystals have the same radius rt after an elapsed time t. (b) Nucleation is sporadic. Crystal A has had enough time to reach point X, while B has not, although both originate in the same ring a distance r from x.

Crystallization conditions such as temperature, solvent, and concentration can influence crystal form. One such modification is the truncation of the points at either end of the long diagonal of the diamond-shaped crystals seen in Fig. 4.11b. Twinning and dendritic growth are other examples of such changes of habit. 

Crystal growth modifiers have been employed to improve filterabiHty and water retention of Ca(OCl)2 2H20, which typically crystallizes as fine plates. Addition of zinc dust or salts produces larger square- and diamond-shaped, untwinned dihydrate crystals (215). Coarse prismatic crystals are obtained by use of carbohydrates and carboxyHc acids and thek salts (216). 

In the analysis of crystal growth, one is mainly interested in macroscopic features like crystal morphology and growth rate. Therefore, the time scale in question is rather slower than the time scale of phonon frequencies, and the deviation of atomic positions from the average crystalline lattice position can be neglected. A lattice model gives a sufiicient description for the crystal shapes and growth [3,34,35]. 

M. C. Liang, C. W. Fan. Three-dimensional thermocapillary and buoyancy convections and interface shape in horizontal Bridgman crystal growth. J Cryst Growth 180 5% , 1997. 

F. Otalora, J. M. Garcia-Ruiz, A. Moreno. Protein crystal quality studies using rod-shaped crystals. J Cryst Growth 168 93>, 1996. 

Fig. 2.2. A diamond-shaped crystal showing four sectors and the folds lying parallel to the (110) growth faces...

In some cases shape-control has also been achieved tetra( -octyl)ammonium glycolate transforms Pd(N03)2 predominantly into trigonal Pd particles [186]. Recent work has confirmed that the colloidal protective agents not only prevent particle agglomeration but even provide control of the crystal growth during particle synthesis (see e.g., Ref. [187-191]). The drawbacks of this route are the restriction to noble metal salts and the limited industrial availability of A-(octyl)j RC02. 

Shape Control Based on the Crystal Growth Habit... 

Moreira, M.L., Andres, J., Varela, J.A. and Longo, E. (2009) Synthesis of fine microsized BaZr03 powders based on a decaoctahedron shape by the microwave-assisted hydrothermal method. Crystal Growth and Design, 9, 833-839. 

Nadagouda, M.N. and Varma, R.S. (2008) Microwave-assisted shape-controlled bulk synthesis of Ag and Fe nanorods in polyfethylene glycol) solutions. Crystal Growth and Design, 8, 291-295. 

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