Abstract Scope |
High permittivity has been discovered in unpoled single boron fiber (100 μm diameter, with a 17-µm diameter tungsten-based core) exhibiting resistivity 9.8×10-4 Ω.cm. This is a conductive polarizable material. The relative permittivity is 8.2×104 (10 kHz), due to charge carrier polarization, as predicted by Jonscher for conductors (1999). Immediately prior long-time (≤60 min) electrical shorting decreases the permittivity only by 6%, but the permittivity is completely restored upon subsequent open circuiting. The short circuiting causes slight capacitor discharge and subsequent open circuiting causes self-charge. The long time for slight discharge supports the stability of the charged state, which is due to the interaction of a fraction of the carriers with the atoms, as previously shown for carbons. Compared to boron fiber, carbon fiber has lower relative permittivity (1.2×104), but comparable resistivity (1.5×10-3 Ω.cm). The capacitance is in the pF range, due to the conductivity and the consequent low electric field. |