Significantly enhanced electrical properties in CaBi₂Nb₂O₉-based high-temperature piezoelectric ceramics

A synergetic effect of Li/Nd at the A site and W/Mn at the B site co-substitution on electrical properties of calcium bismuth niobate (CaBi2Nb2O9, CBNO)-based ceramics is proposed in this paper. CBNO primarily shows mixed p-type and ionic conduction due to a trace of oxygen vacancies (VO••). Both bulk resistivity (ρb) and activity energy (Ea) for conduction are dramatically increased by the co-substitution in Ca0.92(Li1/2Nd1/2)0.08Bi2Nb2-x(W3/4Mn1/4)xO9 [CBNO-LN-x(WM), x = 0-0.02]. Consequently, the modified compositions almost show an intrinsic conducting mechanism due to a significant suppression of the VO•• concentration. Furthermore, the synergetic effect of Li/Nd at the A site and W/Mn at the B site greatly improves the piezoelectricity coefficient (d33), which is up to ∼21.1 pC/N in the optimized composition [CBNO-LN-10(WM)]. This combined with a high Curie temperature (TC = ∼946 °C) and high resistivity indicates that CBNO-LN-10(WM) is a good promising material in high-temperature piezoelectric applications.