Frequency dependence of dielectric nonlinearity in PMN relaxor system

The linear ε1∗ and the third harmonic complex dielectric constant ε3∗ in PbMg13Nb23O3 (PMN) single crystal were measured as a function of frequency and temperature in a small electric field. The dielectric dispersion of ε3∗ was studied and the characteristic relaxation time together with the static dielectric nonlinearity were determined as a function of the temperature. The static dielectric nonlinearity βs is increasing with decreasing temperature in the temperature range 266–242 K, while the relaxation time follows the Vogel–Fulcher law.