Dielectric relaxation in silica glass

Dielectric dispersion in silica glasses with various OH concentrations were investigated from 20 Hz to 1 MHz in the temperature range from 30 to 1000 degrees C. Dielectric relaxation, which could be attributed to the elementary process of structural secondary relaxation caused by OH motion, has the activation energy between 2.3 and 2.6 eV. ac and dc electrical conductivities and diffusion coefficient of OH have been deduced from the imaginary part of the dielectric constant. The ac electrical conductivity shows the characteristic feature as is usually observed in amorphous solids. The dc electrical conductivity and diffusion coefficient of OH derived therefrom obey the Arrhenius law with the activation energy of 1.0 +/- 0.2 eV in the temperature range from 350 to 1000 degrees C. (C) 1999 American Institute of Physics. [S0021-8979(99)05223-8].