Non-Linear Dielectric Susceptibility Near to the Field-Induced Ferroelectric Phase Transition of K_0.937Li_0.063TaO₃

Abstract Linear and non-linear dielectric susceptibilities, χ 1, χ 2 and χ 3, of field-cooled K0.937Li0.063TaO3 are investigated at and above the sharp first-order ferroelectric phase transition temperature, T 1 ≈ 105 K, as corroborated by the divergence of the first harmonic, χ 1(T). The second harmonic, χ 2(T), indicates the conversion from spontaneous to remnant screening polarization as T exceeds T 1. After aging the sample at temperatures up to 480 K this is replaced by an intrinsic polarization (‘self-poling field’), which is robust against poling of either sign. The third harmonic, χ 3(T), mirrors the distribution of Li+ clusters of various sizes. They are slowly relaxing and aging, but do not form a dipolar glass in the precursor range, T > T 1. Keywords: Doped incipient ferroelectricsnon-linear susceptibilitypolar clustersagingPacs: 77.80.Bh64.70.Kb77.20.+y78.20.20.Fm Acknowledgment WK thanks the Foundation for Polish Science for an Alexander-von-Humboldt Honorary Fellowship.