Investigation of Improved Reliability in BaTiO₃ -Based Ceramics via Two-Step Sintering by Impedance Spectroscopy and Schottky Barrier Model

Abstract

The ceramics prepared by conventional sintering (CS) method and two‐step sintering (TSS) method are investigated in the temperature range of 490–570 °C through impedance spectroscopy, which is correlated with the improved reliability of TSS specimen. There is an improvement in the resistances (Rg and Rgb) of TSS specimen mainly due to the reduced grain size. And according to the grain boundary double Schottky barrier model, not merely the smaller potential barrier height (Фgb) but also the larger depletion layer thickness (δgb) for TSS specimen indicate that the effective concentration of charged acceptor dopants and hence oxygen vacancy concentration in TSS specimen are much lower than these in CS specimen. These facts can account for the improved reliability in BaTiO3‐based ceramics via two‐step sintering.

Simultaneously Achieved Ultrastable Dielectric and Energy Storage Properties in Lead-Free Bi0.5Na0.5TiO3-Based Ceramics

“…More importantly, a low-frequency tail appears for the BNT–NN–SZM 0.50 and BNT–NN–SZM 0.75 samples, which is due to the particular charged defects (in this case, oxygen vacancies) blocked at the grain boundaries and electrodes . Grain boundaries can be considered as back-to-back double Schottky barriers, and the corresponding depletion layer thickness (δ gb ) and potential barrier height (Φ gb ) can be calculated based on the impedance measurements, which can be further used to estimate the oxygen vacancy concentration ([V O •• ] ∝ Φ gb /δ gb 2 ) . Here, we define Φ gb /δ gb 2 as the nominal [V O •• ] and make a comparison among samples with different Mg contents (Figure b).…”

“…To characterize oxygen vacancies' contribution more directly, the impedance analysis was adopted to separate . 24 Here, we define Φ gb /δ gb 2 as the nominal [V O…”