Electrical Relaxation in Na ₂ O·3SiO ₂ Glass

Abstract

The electrical relaxation associated with alkali diffusion in Na 2 O·3SiO 2 glass was studied from 0.2 Hz to 700 kHz at –1° to 163°C. A formalism for analysis of electrical relaxation in conducting dielectrics which associates the nonexponential decay of the electric field to zero and the dispersions in the dielectric constant and the conductivity with a distribution of relaxation times for the electric field was developed and is shown to be in qualitative accord with current molecular theories of electrical relaxation in alkali silicate glasses. A relation between the dc conductivity, the limiting high‐frequency dielectric constant, and the average electric field or conductivity relaxation time was derived and is verified experimentally for the Na 2 O·3SiO 2 glass. The distribution of electric‐field relaxation times for the glass is broad, asymmetric on a logarithmic scale, and weighted in favor of the shorter relaxation times; the distribution narrows with increasing temperature. A reduced electrical relaxation curve which can be used to compare electrical and mechanical relaxations in Na 2 O·3SiO 2 glass was generated.