Engineering of Lead-Free Piezoelectrics in Alkali Niobate Ceramic System: Improvement in Density by Two-Step Mixing Process

Abstract

Lead-free Li0.06(Na,K)0.94NbO3 (LNKN) piezoelectric ceramics were sintered by a new process, “two-step mixing process”, in which a part of alkali source powders (RA) was initially preserved and mixed with the rest matrix powders after the calcinations step, in order to improve bulk density. Sintering of the LNKN ceramics was improved by this process, and the sample with RA = 5% had the highest bulk density of 4.34 g/cm3 (ca. 95%TD). The pore shape and the fracture morphology of the samples suggested the formation of a liquid phase. The present results indicated that the two-step mixing process was an universal approach for improvement in the densification of alkali niobate ststem.