Microstructure, piezoelectric and ferroelectric properties of Mn-added Na_0.5Bi_4.5Ti₄O₁₅ceramics

Lead-free piezoelectric ceramics Na0.5Bi4.5Ti4O15+ x wt% MnCO3have been prepared by a conventional sintering technique, and their structure, piezoelectric and ferroelectric properties have been studied. Our results show that MnCO3is effective in promoting the grain growth and densification of the ceramics. After the addition of MnCO3, the remanent polarization Pr, piezoelectric coefficient d33, electromechanical coupling coefficient kpand mechanical quality factor Qmof the ceramics are increased, whilst the loss tangent tanδ is decreased. For the ceramic added with 0.375 wt% MnCO3, the dielectric and piezoelectric properties become optimum: d33= 28 pC/N, kp= 0.06, Qm= 3290, εr= 140 and tanδ = 0.3%. Our results also demonstrate that the ceramic exhibits a good thermal stability up to around 500 °C.