Electrical conductivity of B∼4.3C boron carbide up to 9 GPa and 1273 K

Boron carbide belongs to the group of covalently bonded solids in the B–C system, with a high melting point and hardness, is light, resistant to wear and has good semiconductor properties hence is an important material for a range of technical applications. We have carried out electrical conductivity measurements of B∼4.3C up to 9 GPa and 1273 K. This range of pressure is much lower than the phase transition at 33.2 GPa, suggesting that elastic deformation is the essential effect on the electrical conductivity. Depending on temperature, relaxation processes confirm structural changes at the 712 K phase transition. Stronger relaxation at higher temperature suggests a further phase transition of similar kind. Impedance spectroscopy shows anomalous behavior at 8.8 GPa and 920 K. Missing concerning significant effects in the DC conductivity precludes the interpretation as phase transition; the explanation remains open. [Display omitted] •High pressure and temperature impedance spectroscopy measurement has been applied to study phase transitions in B∼4.3C.•Impedance spectroscopy is an effective tool in studying phase transitions in semiconductors that are difficult to detect.•Nyquist plots of B∼4.3C at 8.8 GPa indicate a pressure-induced change of the electronic transport properties.•Relaxation processes in B∼4.3C confirm structural changes at the 712 K phase transition.