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 K_0.937Li_0.063TaO₃ 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 ferroelectrics
• non-linear susceptibility
• polar clusters
• aging

Pacs:

• 77.80.Bh
• 64.70.Kb
• 77.20.+y
• 78.20.20.Fm

Acknowledgment

WK thanks the Foundation for Polish Science for an Alexander-von-Humboldt Honorary Fellowship.