Microstructure, piezoelectric and ferroelectric properties of Mn-added Na0.5Bi4.5Ti4O15 ceramics

Lead-free piezoelectric ceramics Na0.5Bi4.5Ti4O15 + x wt% MnCO3 have been prepared by a conventional sintering technique, and their structure, piezoelectric and ferroelectric properties have been studied. Our results show that MnCO3 is 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 kp and mechanical quality factor Qm of 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.