High-power impedance spectroscopy for lead-free alkali niobate piezoceramics

Impedance spectroscopy for piezoceramics under high-power application was investigated. Impedance spectra under bipolar high electric field were completely different below and above TC. Below TC, high-power impedance spectra could be successfully fitted to a three resistance-constant phase element (3 R-CPE) equivalent circuit. Above TC, however, a 2 R-CPE equivalent circuit was sufficient to fit with high-power impedance spectra. For this reason, there was another relaxation factor caused by high-power application in the ferroelectric phase. From the high-power impedance spectra below TC, the nonlinear response of capacitance under a high electric field was calculated. Hence, domain wall motion would appear as a relaxation factor. Subsequently, high-power impedance spectra before and after cyclic unipolar fatigue treatment were compared. Considering the assumption that domain wall motion appeared as a relaxation factor, the capacitance caused by domain wall motion was decreased after cyclic fatigue. In conclusion, we believe that domain wall pinning could be evaluated by separating other electrical properties. In this work, the measurement possibility by impedance spectroscopy for high-power application for piezoceramics was investigated.