DIELECTRIC RESPONSE OF SOME FERROELECTRICS AT LOW-FREQUENCIES I

The dielectric response of ferroelectric PST ceramics and of TGS singl e crystals was measured in the seldom reported range 10(-3)-10(4) Hz. Their complex dielectric susceptance (X) over tilde(omega) = X'(omega) - iX ''(omega) shows, after removal of processes such as direct-curre nt conductivity, Low-Frequency Dispersion and certain dipolar features , underlying regions of relatively ''flat'' frequency dependence obeyi ng the ''universal'' fractional power laws (X) over tilde(u)(omega) pr oportional to (i omega n(-1)) extending over five to seven decades of frequency. The magnitude of the power-law exponent n depends weakly on temperature and on the magnitude of the permittivity and depends only slightly, if at all, on the ferro- or para-electric stale of the samp le. We note that this residual universal response is seen by us more c learly in ferroelectric materials than in any others. The significance of these results is discussed.