Diameter crystallizer

The polycrystaUine EGS is converted to siagle-crystal silicon via the C2okralski (CZ) crystal growing process, based on the solidification of silicon atoms from the Hquid phase at a moving iaterface. Volume production of 200-mm diameter crystals is standard. Development of crystals having diameters of up to 400 mm has been predicted (3). 

Scintillators like NaI(Tl) can be made position-sensitive for applications like 2D-ACAR (section 7) and medical imaging [19]. Light from a large-diameter crystal is detected by a close-packed array of PM tubes. 

P. Sabhapathy, Report on Computer simulation of flow and heat transfer in CG6000 during 144mm diameter crystal growth with 16-in hot zone . It is an internal report at Kayex Inc., July 1998... 

Wind of moderate speed can drag snow crystals on the surface, or lift them so that they undergo saltation or become suspended in air. " Saltation, i.e. bouncing and breaking on the snow surface, leads to grain fragmentation and sublimation and crystals are usually 0.1 to 0.3 mm in diameter. Crystals accumulate in wind-sheltered areas, such as the lee of... 

Figure 5 represents a typical evolution of the dislocation pattern during the deformation. The simulation was performed in a 20 mm diameter crystal, with 2 initial basal planes activated (one system in each plane) at the beginning of the deformation. It clearly appears that the double cross-slip mechanism propagates the plasticity in many other basal planes. One can also notice the asymmetry in the plane expansion due to the dislocation interactions. 

Manganese(II) thiocyanate (0.05 mole, 8.55 g) is dissolved in 100 mL of water. Then 1,2,4-triazole (0.1 mole 6.91 g), dissolved in 50 mL of water, is added. A few drops of concentrated nitric acid are added and the solution is heated to boiling, cooled immediately to room temperature and stored for several days in a desiccator above phosphorus pentoxide. The yield of the product, recovered by Filtration, washed with water and dried under vacuum is —12 g or about 75%. The crystals have the shape of flat rhombi, almost squares, with a thickness of about one-fifth of the largest diameter. Crystal diameters may vary from 1-10 mm depending upon the preparative technique. Crystallization of this compound occurs more slowly than for the compounds containing other metals. 

It was clearly observed that the phenomenon of delayed crystallization was directly related to the size of the dispersed droplets [Koutsky et al., 1967]. Only the smallest droplets showed crystallization at much larger undercooling droplets having a sufficiently large diameter crystallized at temperatures approaching the bulk crystallization... 

P-quartz. The P-quartz crystals are <0.1 pm in diameter. Crystal sizes below the wavelength of visible light (A. = 0.7-0.4 pm), a good match in refractive index between the glass and the crystal phase, coupled with a low birefringence result in high transparency. Table 26.4 lists the compositions and applications of some commercial transparent LAS glass-ceramics based on P-quartz. 

FIGURE 5.16. Diffusivity data for n-butane and propane in 5A zeolite crystals showing comparison between NMR sclf-diffusivities ( ) and corrected diffusivilies from uptake rate measurements (Dq)- X, 0. 55- and 27.5-jam diameter crystals synthesized by Yucel O, , 34-and 7.3-/xm crystals synthesized by Yucel +, 3.6-ftm Linde crystals A 2l.5- im crystals synthesized by Shdanov ( ). (From ref. 54, with permission.)... 

Steps on surfaces of polyDCHD crystals (a) SEM micrograph of 15 fim diameter crystal (b) TEM micrograph of 100 nm diameter crystal showing molecular steps. 

This method, involving the critical strain criterion, has been widely studied on non-rare earth metals as a result of which it was established that if the applied strain was less than this critical amount then no recrystallisation occurs on subsequent annealing too much strain can cause too many grains to nucleate. That this criterion applies equally well to the rare earth metals was clearly illustrated by the work of Pederson et al. (1965) on Gd. A critical strain of 1-2% was established on a tapered tensile specimen, and when such a strain was applied to a cylindrical specimen followed by an anneal at 1200°C for 3 days large (2.5 X 1 cm diameter) crystals grew. A similar specimen strained 0.66% did not recrystallise. 

For growth in the Ekz-2405 puller the crystal heights equal to 300 and 700 mm have been considered with more than a two-fold reduction of the melt depth for the latter (Figs. 6.8(c) and (d)). The resolved turbulent energetic vortices (Fig. 6.8(b)) are of the same scale of about 3 cm as in 100-mm diameter crystal... 

Fig. 6.9 The temperature distribution along the melt/crucible interface for 100-mm diameter crystal growth.

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