Breakdown performance of potassium-sodium niobate piezoceramics copped with oxides

Abstract

In the work, the CuO, Fe2O3, ZnO, and Al2O3 are doped in the potassium-sodium niobate (KNN) to investigate their effects on the breakdown strength (EB) through in situ decomposition reaction on the KNN particles. The results suggest that the EB increases to some extent, thanks to the addition of oxides. Particularly, the addition of ZnO improves the EB by 34.08% compared with pure KNN ceramics. The X-ray diffractometry, SEM, temperature-dependent dielectric constant, complex impedance spectrum, breakdown strength test, and energy band structure are employed for the EB investigation. The addition of Fe2O3 and Al2O3 can reduce the grain size of ceramics while CuO leads to grain growth. The relative density, dielectric constant, activation energy (Ea), and relaxation time (τ) of the ceramics are enhanced by the addition of Fe2O3, ZnO and Al2O3. Among these factors, the relative density is helpful for the improvement of the EB. Additionally, the featured energy band structure contributes to such improvement.