The internal friction at low temperatures has been measured on polycrystalline samples of -B, B 4 C, B 13 C 2 , and B 9 C. As the carbon deficiency increases in the boron carbides, the internal friction approaches that of amorphous solids. For comparison, the internal friction of amorphous B 9 C, pr
Lattice Vibrations of Boron Carbide
β Scribed by Koun Shirai; Shuichi Emura
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 271 KB
- Volume
- 133
- Category
- Article
- ISSN
- 0022-4596
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β¦ Synopsis
The vibrations of boron carbide B 13 C 2 have been studied by the valence force model. The 1560-cm Ψ1 band is ascribed to the antisymetric stretching of the linear chain, and thereby it is IR active only. Large angle-bending forces of the carbon atoms are estimated to agree with the experiment. This conclusion is reasonable, by considering the strong covalent character of the linear chain. At the cost of forming strong covalent bonds in the linear chain, the character of icosahedral bonding is weakened. The decrease in most Raman bands of boron carbides compared with those of -boron can be understood on this basis.
π SIMILAR VOLUMES
An investigation of sintering kinetics of boron and boron carbide is presented. The in6uence of the powder size distribution on the temperature dependence of sintering, on reaching a high 5nal density, and on gaining a homogeneous grain size has been shown. The results on the -rhombohedral usage in