Enhanced dielectric and piezoelectric properties of Mn modified 0.65(Bi0.95La0.05)FeO3-0.35Pb(Ti1-xMnx)O3 ceramics

Piezoelectric ceramics of 0.65(Bi0.95La0.05)FeO3-0.35Pb(Ti1-xMnx)O3 (BLF-PTM) (x = 0, 0.01, 0.02, 0.03 and 0.04) were prepared by the conventional solid-state reaction method. X-ray diffraction analysis reflected that BLF-PTM ceramics showed pure perovskite structure with the coexistence of rhombohedral and tetragonal phases, and tetragonal distortion decreased slightly with Mn content. Dielectric and piezoelectric properties of BLF-PTM ceramics were enhanced obviously by Mn doping. The Curie temperature TC, depolarization temperature Td, dielectric constant εr (1 kHz), dielectric loss tanδ (1 kHz), piezoelectric constant d33, planar electromechanical coupling factor kp and mechanical quality factor Qm for BLF-PTM ceramics of x = 0.02 were 534, 475 °C, 230, 0.003, 100 pC/N, 0.29 and 560, respectively. The dielectric loss was reduced to one-sixth while piezoelectric constant was improved to one and half those of BLF-PTM ceramics without Mn modification. The depoling temperature was about 300 °C higher than that of Pb(Zr,Ti)O3 (PZT) based ceramics. Our results indicated that BLF-PTM ceramics were promising candidates for high temperature piezoelectric applications.