The complex dielectric permittivity of solid solutions (1-x)PbZrO3+xK(0.5)B
i(0.5)TiO(3) with x=0.15-0.7 in the low temperature range has been studied.
Two diffused relaxation maxima of tg delta were observed, the nature of wh
ich is the interaction between the ferroelectric domain walls and point def
ects. For the explanation of experimental results the physical model has be
en developed.