Improvement effects of sinterability due to B-site excess composition in (K,Na)NbO3 system ceramics

Abstract

The sinterability of Bi- A nd Cu-doped (K,Na)NbO3 (KNN) ceramics fabricated from B-site excess calcined powder was investigated. Contrary to conventional reports regarding the sinterability of Bi-free KNN ceramics, it was found that the sinterability was improved with the increase in the B-site excess ratio. To elucidate the reason for this observation, X-ray diffraction and X-ray photoelectron spectroscopy measurements were performed. The formation of K4CuNb8O23 was observed in some B-site excess samples. In addition, an apparent change in the valence state was detected, which is thought to be due to the substitution of the A-site ions in KNN with the Bi atoms.