Poly crystalline diamond

Many problems must be solved before practical, reliable, and cost-effective diamond semiconductor devices become available. Yet, the prospects are good, particularly if epitaxial single-crystal or highly oriented poly crystalline diamond can be effectively produced by CVD.P5]... 

In the above analysis, we used the concept of space charge layer, to be more precise, a depletion layer that would form in a doped, wide-gap semiconductor contacting another phase (a metal, an electrolyte solution, or vacuum). The poly crystalline diamond/metal junctions (where metal is Au, Pt, Pd, etc.) often show rectifying properties [67, 68] and their capacitance characteristics resemble those of a diamond/electrolyte solution junction. 

Fig. 5.125. Photocurrent spectrum of a poly crystalline diamond electrode in contact with an aqueous solution of 0.5 M H2SO4 at an electrode potential of Enhe = 0-05 V (based on data in [721])...

Poly crystalline Diamond and Cubic Boron Nitride... 

Figure 3 compares uncoated cemented carbide tuning tools (HW KIO) with TiN (HC TiN) and diamond-coated (HC DP) ones and tools with a poly crystalline diamond insert (DP). The tools have been used for external cylindrical turning at... 

Another candidate for a useful material from very high pressure synthesis is the gem material, jadeite (NaAlSi206). The natural material of Imperial quality can cost as much as 2000 per carat. Jadeite can be synthesized at about 30 kb and above in equipment similar to that used for diamond growth, and it has been made into pieces of jewelry. Since jadeite is used as a poly-crystalline aggregate, synthesis is essentially hot pressing and sintering, much simpler than if single crystals were needed. However, it does not appear to be a commercial product in competition with the natural supply. 

A SEM image of diamond particles is shown in Figure 9.15. Unlike past works, diamond film surfaces were well facetted with (111) and (100) faces, or consisted of cubo-octahedrons. Under certain conditions, either (111) or (100) faces of diamond particles were nearly parallel to the substrate surface. It is of intrigue that the (1 ll)-oriented diamond grains have hexagonal faces, as seen in Figure 9.15, rather than triangles that were seen in Refs. [186, 187]. Thus, both (111)- and (100)-textured diamond films were demonstrated to be synthesized on poly-crystalline Cu foils. 

Poly crystalline and Chemical Vapor Deposited Diamond... 

Figure L3 Strain e versus sin v fot a poly-crystalline tungsten film. Circles as-deposited diamonds, squares and triangles increasing loading states (the specimens being tensile...

Preparation and Characterization of Poly crystalline Chemical Vapor Deposited Boron-doped Diamond Thin Films... 

Many elements can give rise to more than one elementary substance. These may be substances containing assemblages of the same mono- or poly-atomic unit but arranged differently in the solid state (as with tin), or they may be assemblages of different polyatomic units (as with carbon, which forms diamond, graphite and the fullerenes, and with sulfur and oxygen). These different forms of the element are referred to as allotropes. Their common nomenclature is essentially trivial, but attempts have been made to develop systematic nomenclatures, especially for crystalline materials. These attempts are not wholly satisfactory. 

Vinylidene fluoride (VF2) as well as vinyl fluoride (VF) resemble more ethylene than other vinyl monomers in regard to the properties and can also be polymerized in a manner analogous to that of ethylene. The first successful polymerization of vinylidene fluoride was reported by Du Pont in 1948 [517]. Poly(vinylidene fluoride) (PVF2 or PVDF) is commercially available from various companies (Kureha Chemical Co., Pennalt Chemicals Corp., Solvay Co., Siiddeutsche Kalkstickstoff-Werke AG now Degussa, Diamond Shamrock, Du Pont) since 1965 under the trade names KF, Kynar, Foraflon, Vidar, and Dalvor, respectively. VF2 can be polymerized by free-radical initiators to give high-molar-mass, crystalline polymers. 

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