Acceptor doping effects in (K0.5Na0.5)NbO3 lead-free piezoelectric ceramics

In this paper, the effects of acceptor dopants on the synthesis, sintering and properties of KNN ceramics were studied for (K0.5Na0.5)(Nb0.994A0.006)O3−δ (A=Ge4+, Ga3+, Zn2+, Mn2+, Ni2+, and Cu2+) ceramics. The results reveal that the eutectic phase(s) is (are) formed between the acceptor oxide and alkali metal carbonate, thereby significantly improving the sinterability of the materials. Compared to the trivalent and tetravalent acceptor dopants, divalent dopant can lead to higher Qm values, most likely due to the formation of defect complexes.