Dielectric loss in boron

Abstract

The temperature dependence of the dielectric loss (tgδ) in β-B was studied at temperatures ranging from −196 to 350 °C and at frequencies of 1–10 4 Hz. The curve of the temperature dependence of dielectric loss in an electric field with a frequency of 50 Hz showed two relaxation maxima at −65 and −45 °C characterized by activation energies of 0.18 eV and 0.23 eV respectively. It was established that by annealing boron in H 2 at 700 °C for 1 h the peak of dielectric loss found at −65 °C increased whereas the relaxation maximum observed at −45 °C completely disappeared. In an electric field of 10 kHz, a relaxation maximum with an activation energy of 0.6 eV appeared at 100 °C. The height of this peak correlated to the change in the carbon content of the samples investigated. A non-relaxation peak of tgδ was observed at 300 °C. Around this temperature, the temperature dependence curve of the capacitance passed through a maximum. It was assumed that the processes of absorption of the a.c. electric field energy are caused by the redistribution of the electrically active gas admixtures and of carbon under the effect of the electric field voltage.