Anomalous Behavior of the Dielectric and Pyroelectric Responses of Ferroelectric Fine-Grained Ceramics

TL;DR

This study investigates the unusual dielectric and pyroelectric behaviors of fine-grained BaTiO3 ceramics, revealing temperature-dependent inhomogeneous ferroelectric states and complex conduction mechanisms using advanced thermal and electrical probing techniques.

Contribution

It uncovers the anomalous dielectric and pyroelectric responses in ferroelectric ceramics and models these phenomena with core-shell and effective medium approaches, highlighting internal barrier-layer effects.

Findings

Giant dielectric permittivity exhibits anomalous temperature behavior.

Spatially inhomogeneous counter-polarized ferroelectric states are observed.

Frequency-dependent transition in electro-transport mechanisms is identified.

Abstract

We revealed the anomalous temperature behavior of the giant dielectric permittivity and unusual frequency dependences of the pyroelectric response of the fine-grained ceramics prepared by the spark plasma sintering of the ferroelectric BaTiO3 nanoparticles. The temperature dependences of the electro-resistivity indicate the frequency-dependent transition in the electro-transport mechanisms between the lower and higher conductivity states accompanied by the maximum in the temperature dependence of the loss angle tangent. The pyroelectric thermal-wave probing revealed the existence of the spatially inhomogeneous counter-polarized ferroelectric state at the opposite surfaces of the ceramic sample. We described the temperature behavior of the giant dielectric response and losses using the core-shell model for ceramic grains, effective medium approach and Maxwell-Wagner approach. The superparaelectric-like state with a giant dielectric response may appear due to the internal barrier-layer capacitance effect, while the step-like thermal activation of localized polarons in the semiconducting grains is not excluded. The elucidation of the state microscopic origin requires measurements in the frequency range above 1 MHz.