Single crystal metallic ceramics

The most important application of boron is to make fibers or whiskers of single crystal or ceramic crystal. The addition of boron to metals, alloys, or other solids, imparts resistance to plastic flow, and thereby produces unusual strength in the material. Amorphous boron is used in rockets as an igniter, and in pyrotechnic flares to give green color. Many boron compounds, such as borax, boron hydrides, and boron hahdes, have important commercial applications (see individual compounds). 

T Epicier, Y Kumashiro. A contribution to the experimental study of the crystallography and ordering phenomena in some transition-metal carbides Part II Applicability of high-resolution electron microscopy to the study of ordered defects in vanadium carbide single crystals. Adv Ceram 23 677, 1987. 

When there is no distortion in the structure or no change in orientation throughout a crystal, we refer to the structure as a single crystal. A solid consisting of many single crystals with different orientations is called a polycrystalline aggregate. There are also polycrystalline aggregates of multiple phases, as in metals, rocks, and ceramics. 

From the data listed in Table 3, it may be noted that the polarization values of the ceramics are lower than that of the single crystal [7,8] whereas the coercive field is higher. This may be attributed to the existence of the non-ferroelectric layers at the metal-ferroelectric interfaces and grain boundaries. In other way, when the anisotropy of the crystal get stronger, the displacement of ions, which is demanded by polarization inversion, get larger, the coercive field will be stronger. 

The value of of the BaTiO, ceramics is lower than that reported for BaTiOj single crystal [9] (along [100] =4 000). This may be due to the structural and compositional variances. Meanwhile, the size of crystalline particle may affect the dielectric constant , that is, when the particle size is lower than certain value, the constant will decrease with the decrease of the size. In addition to those mentioned above, porosity and the existence of low dielectric constant affect the non-ferroelectric layers at the metal-ferroelectric interface and the grain boundaries. 

Only a few studies [453,543-547] have been carried but on the photoelectrochemical behaviour of YBCO ceramics and single crystals. In nonaqueous media, in the absence of degradation, the data show that the usual concepts of photoelectrochemistry of p-type semiconductors apply to those systems. Such studies have not yet been actively developed, probably because of the high sensitivity of photoelectrochemical processes to the nature of materials. Reproducibility of data for such complex systems as HTSC oxides is an issue. At the same time, the photoassisted electrochemical processes on HTSC electrodes can lay the basis for certain effective technologies. This is especially true for the photoelectrochemical etching and metallization which prove to be extremely effective as applied to semiconductors [503,504]. 

With the development of cermets (ceramic-metallic composites materials) and glassy ceramics, the borderlines between ceramics and metals and ceramics and glasses have become somewhat blurred. Modern ceramics include both materials and products, which range from single crystals and dense polycrystalline materials by way of glass-bonded composites to foams and glassy substances. 

Preparation of Metallic Ceramics 17.3.9.2. Metallic Carbides 17.3.9.2.3. Single Crystal Growth. 

Available forms Powder (platinum black), single crystals, wire (2 by 0.05-0.005 inches diameter) special composition for electronics, metallizing, and decorating ceramics and metals. 

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