SPACE-CHARGE RELAXATION AND CLUSTERING IN YTTRIUM DOPED BAF2

Characteristics of high temperature ionic thermocurrent (HT ITC) in Ba F2:Y were studied by varying yttrium concentration. A thermal sampling ITC (TS ITC) method was used to decompose the HT ITC band and reveale d that the high temperature part of the band consists of a single and intense ITC one. The HT ITC spectra could be analyzed by a space charg e how model with a relaxation time of tau(T) = tau(oo)T(exp)(E-a/kT) W ith the aid of a usual ITC method, a relation between the temperature of maximum ITC (T-m) and yttrium concentration (n) could be expressed in a form of T-m = T-mo - alpha n(1/3). Furthermore, the activation en ergy (E-a) follows E-a(n) = E-ao - gamma n(1/3) and was explained by t he Lidiard-Debye-Huckel (LDH) model. (C) 1997 Elsevier Science Ltd. Al l rights reserved.