HIGH-FREQUENCY DIELECTRIC-RELAXATION OF A KTA0.6NB0.4O3 CERAMIC

The dielectric permittivity, epsilon = epsilon' - i epsilon '', of a KTa0.6Nb0.4O3 ceramic was measured in the frequency and temperature ra nges 10(6) to 10(9) Hz and 298 to 450 K, respectively. A dipolar-type relaxation was reported. A minimum of the relaxation frequency occurs close to the ferroelectric Curie-temperature T-c. The complex plane pl ots epsilon(r)('') vs epsilon(r)' characterize a relaxation with a Col e-Cole behavior: epsilon(omega) = epsilon(infinity) + epsilon(s)-epsi lon(infinity)/1+(i omega/omega(1))(1-alpha).