We found that, at the so-called diffuse phase transition in relaxer ferroel
ectrics, the dielectric permittivity epsilon obeys the relation epsilon(A)/
epsilon = 1 + 0.5(T - T-A)(2)/delta(A)(2) in a wide temperature range above
the temperature of permittivity maximum T-m (T-m > T-A). The parameter del
ta(A) remains invariant with the variation of measurement frequency and cha
racterizes the diffuseness of the transition. (C) 2000 Elsevier Science Ltd
. All rights reserved.