Melting single crystal

The presence of convection also affects crystal growth from the melt. Single crystals of Te-doped InSb were grown from flic melt on Sivlah. The crystals obtained in space were free of striations caused by convection-driven growth rate fluctuations that are normally seen on eanh. future space experiments will examine the grow th of electronic materials such as GaAs from a sululion subjected to an electric current. 

Double molybdates and tungstates of Rb with In, RbIn(Mo0 2 nd RbIn(W04)2, together with KIn(W04)2, have been prepared by crystallization from solution in a melt. Single crystals of NaIn(Mo04)2 have also been obtained. They melt (with some decomposition) at 785 °C, and belong to the triclinic space group Pi (a = IAS, b =7.18, c = 14.90 A a = 92°,... 

Gor2] fee lattice (X. Alloys obtained from melt. Single crystals by chemical transport reaction I2 as carrier gas). Lattice parameter obeying Vegard s law. 

The advantages of this method are twofold (i) It is possible to observe minute changes in colour and structure before and during the process of melting. (2) It is possible to use a single crystal which, e.., is often obtained from a semi-micro sublimation. 

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. 

Single-crystal siHcon can also be grown from various fluxes and by a combination of electrolysis and fluxes at temperatures weU below the melting point of pure siHcon (16). The main disadvantages are the inclusion of the flux in the crystal and the poor crystal quaHty. Potential advantages are a decrease in growth temperature and purification during electrolysis. 

Anatase and mtile are produced commercially, whereas brookite has been produced by heating amorphous titanium dioxide, which is prepared from an alkyl titanate or sodium titanate [12034-34-3] with sodium or potassium hydroxide in. an autoclave at 200—600°C for several days. Only mtile has been synthesized from melts in the form of large single crystals. More recentiy (57), a new polymorph of titanium dioxide, Ti02(B), has been demonstrated, which is formed by hydrolysis of K Ti O to form 20, followed by subsequent calcination/dehydration at 500°C. The relatively open stmcture... 

Purified polycrystalline CVD siUcon from this reaction is then melted and a single-crystal boule weighing as much or more than 50 kg, and having a diameter up to 20 cm, is pulled from the melt by C2ochralski growth (8). Metallurgical-grade siUcon is not sufficientiy pure for appHcations in electronics... 

We will illustrate the power of MEIS with three simple examples. In addition, we remind the reader of the existence of extensive reviews, and in particular would like to mention some quite recent, beautifiil work on the melting of single-crystal surfaces. ... 

The kind of single crystals discussed above are all made starting from solution. In industrial practice, bulk polymeric products are generally made from the melt, and... 

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