On the dielectric relaxations in crystalline insulators and amorphous systems

Abstract

The Direct Signal Analysis is applied here to the decomposition of the whole TSDC peak in elementary curves with temperature dependencies for the relaxation times either Arrhenius or Vogel-Fulcher in crystalline (SrF 2 :Gd 3+ or La 3+ ) or amorphous materials (Bisphenol A Polycarbonate). The energy histogram obtained after fitting the complex peak gives the profile of the energy distributions ; Lorentzian distributions were found for the simple dipolar peaks and small clusters in crystalline materials, whereas for the β-band in PCBA, the distributions are Gaussian. The high temperature spectrum corresponds for both materials to very narrow distributions both for the Maxwell Wagner polarization originated high temperature peak in SrF 2 or for the glass rubber transition in PCBA. Vogel-Fulcher relaxation times had to be used in the latter case.