Conduction mechanism in boron carbide

Icosahedral Boron-Rich Solids

“…The graphs show the Hall mobility (a) and the electrical conductivity (b) of the boron carbide B 4 C as a function of reciprocal temperature. 3 Note that as the temperature rises both quantities rise in a thermally activated manner, that is, as roughly exponential functions of 1/7"; this is consistent with a conduction mechanism of small-bipolaron hopping. Figure 5 "extra" term increases linearly with temperature.…”

Electronic structures and mechanical properties of boron and boron-rich crystals (Part I)

“…For boron solids, the electronic conduction mechanism is very complicated. For β-rhombohedral boron and boron carbides, there are many models and discussions to account for their unusual behaviours [11,14,27,41,64]. That the electronic transport is conveyed by the hopping of a carrier between defect sites is the only point on which most of researchers can agree.…”

“…Under high pressures, an unusual property of boron carbides is found that the electrical resistivity is increased with increasing pressure [128]. This property was once explained in terms of the small bi-polaron mechanism [11]. However, this mechanism was subjected to criticism [27].…”

“…For the development of superhard material research, deep understanding for the special roles of icosahedron is indispensable. This is especially needed, considering that new applications have been explored in superconductivity [10] and thermoelectric research [11][12][13][14].…”

Effects of Metal Doping on Thermoelectric Properties of Arc-Melted and Hot-Pressed β-Rhombohedral Boron

“…6,7) Furthermore, the conduction mechanism of both pure and metal-doped -Boron is considered to be hopping conduction. In the case of phonon-assisted hopping conduction, 8) which is typical of boron carbide, 9) S have a tendency to increase with increasing temperature. This is because the mobility of carriers is thermally activated, whereas the concentration of carriers is almost constant.…”