where v is the attempt frequency, E the activation energy, k Boltzmann's constant, T the temperature of permittivity maximum and T is the static Freezing temperature.By analyzing the observed data none of reasonable curves could be corresponding to Ep.Furthermore,we have not detected any ferroelectric hysteresis on the sample which is not plotted in the paper.So we may not come to the conclusion that the spinel NiZn ferrites are relaxertype ferroelectrics.