Monocrystalline material

The polycrystalline hydride is frequently pyrophoric, particularly at higher hydrogen contents (up to H2.85), while monocrystalline material appears to be less reactive to air. 

From measurement results, it is possible to identify polycrystalline materials from their structure, texture, porosity, monocrystalline materials on crystallographic orientation and glass, considering the heterogeneity of the vitreous phase. 

The characteristics of monocrystalline diamond films are much more clearly defined. Still polycrystalline films are employed in most cases as the high price interferes with large scale application of the monocrystalline material. Even for thin layers there is no significant change to the essential characteristics of diamond. For this reason as well as to save further material, it is a common practice to employ coated substrates with a film the thickness of micrometers spread on their surface (Section 6.6.1). The endurance of such films against mechanical stress is essentially influenced by two factors Firstly, by delamination (peeUng off) of the film from the substrate, and secondly by normal, gradual wear. 

Polycrystalline silicon and germanium are difficult to obtain (monocrystalline materials, especially germanium, are much more readily available but they rupture by cleavage under stress). Moreover, since they are opaque in the visible, they do not allow safe seating of the windows (see below). 

X10. The next three rows present the viscosity rj, the surface tension, and its tenqterature dependence, in the liquid state. The next properties are the coefficient of linear thermal expansion a and the sound velocity, both in the solid and in the liquid state. A number of quantities are tabulated for the presentation of the elastic properties. For isotropic materials, we list the volume compressihility k = —(l/V)(dV/dP), and in some cases also its reciprocal value, the bulk modulus (or compression modulus) the elastic modulus (or Young s modulus) E the shear modulus G and the Poisson number (or Poisson s ratio) fj,. Hooke s law, which expresses the linear relation between the strain s and the stress a in terms of Young s modulus, reads a = Ee. For monocrystalline materials, the components of the elastic compliance tensor s and the components of the elastic stiffness tensor c are given. The elastic compliance tensor s and the elastic stiffness tensor c are both defined by the generalized forms of Hooke s law, a = ce and e = sa. At the end of the list, the tensile strength, the Vickers hardness, and the Mohs hardness are given for some elements. 

High-temperature electrical conductivity measurements were used to study chemical diffusion in monocrystalline material at 550 to 800C. It was found that the results could be described by ... 

The diffusion of Co in monocrystalline material was found to be a rapid process at semiconductor-device fabrication temperatures. Electronic-grade Ge samples were coated with a radioactive surface source and short-term annealed in a lamp furnace at 600 to 900C. The diffusion coefficients were determined from the penetration profiles of the radioisotope, Co, and could be described by the expression ... 

Serial sectioning was used to study the diffusion of 123sji monocrystalline material with a carrier concentration of about lO /cm. It was found that the concentration profiles were consistent with the existence of 2 diffusion coefficients one which applied near to the surface,... 

The concentration profiles of B which had been diffused, from polycrystalline material, into underlying monocrystalline material were analyzed by means of secondary ion mass spectrometry. The co-diffusion of As and B was studied in an emitter and extrinsic base configuration. In a first poly-Si layer, the diffusivity could be described by ... 

A similar expression (but involving a z instead of atso) also applies to the case of a monocrystalline material. For polycrystalline or powdered samples, on the other hand, the continuous distribution of orientations of the several crystallites with respect to the direction of Bo causes an anisotropic broadening of the resonance spectmm, known as broadening due to chemical shift anisotropy (CSA) [10]. 

In general, industrial HPHT synthesis of diamond produces crystals with size ranging from tens to hundreds of micrometers. Up to now, ordinary mechanical milling of as-grown HPHT diamond (20-50 pm) yields a very small and, thus, commercially expensive fraction of NDs. However, a powder of commercial-type lb-synthetic monocrystalline diamond fabricated for industrial polishing purposes can be used to produce monocrystalline material by crushing, purification, and precision grading to achieve a particle size distribution below 50 nm. ... 

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