Single crystal vapor methods

Bi nanowires have been grown from direct vapor into AM templates with diameters in the range 7 to 200 nm and their galvanomagnetic properties were studied [21]. The grown wires were single crystals. The method of growth is rather simple, the membrane is placed at the mouth of a crucible, which is kept in vacuum and contains molten Bi. 

Several different methods are used commercially to grow single crystals. These methods, which can be divided into melt, solution, and vapor-phase techniques, are summarized in Table 29.2. Here, the operating cost does not include the cost of labor, the skill refers only to the diffi-... 

Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. The Gzochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process. 

If the material whose single crystal we want is volatile or sublimable, then we may choose a vapor-method of crystal growth. These methods have been used for a variety of crystals including ZnS and CdS. In this method, a carrier- gas is most often used for material transport and for the sulfides, H2S is the gas of choice. The following shows a simple apparatus ... 

In addition to sublimation or vaporization, we can also use chemical tremsport as a method of single crystal growth. For example, we could use either of the apparati of 6.12.1. or 6.12.4. to grow a crystal of ZnCl2 by the following reactions ... 

Vapor Methods Used for Single Crystal Growth 292... 

This is comparable to or slightly higher than the values reported for single crystal (11) and polycrystalline Ti02 (12), and much higher than those for the TiC>2 film electrode prepared by other methods such as chemical vapor deposition (13) and oxidation (14) and anodization (15) of Ti metal. The high efficiency of the dip-coated Ti(>2 film may be attributed to the porous nature of the film as described below. 

Shibata, T. Muranushi, Y. Miura, T. Kishi, T. 1991. Electrical characterization of 2H-SnS2 single crystals synthesized by the low temperature chemical vapor transport method. J. Phys. Chem. Solids 52 551-553. 

Vapor grown diamonds are sjmthesized by the CVD method under low-pressure conditions, for which diamond becomes unstable, and it is possible to obtain single crystals of micrometer size. Frequent occurrences of multiply twinned par-... 

The preparation of single crystals. The need for fundamental studies of the mechanical, electrical, and surface properties of carbides and nitrides have necessitated the preparation of single crystals.27 Carbide single crystals are prepared by the Vernouil technique, the floating zone technique, and methods involving precipitation from liquid metals. Nitride single crystals are prepared by vapor transport processes. 

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