Behavior of the dielectric and pyroelectric responses of ferroelectric fine-grained ceramics

Abstract

We demonstrated the correlations between the specific temperature behavior of the colossal dielectric permittivity, unusual electro-transport characteristics, and 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 temperature dependence of the loss angle tangent. The pyroelectric thermal wave probing revealed the existence of the spatially inhomogeneous counter-polarized ferroelectric states at the opposite surfaces of the ceramic sample. We described the temperature behavior of the colossal dielectric response and losses using the core−shell model for ceramic grains, effective medium approximation, and Maxwell−Wagner approach.