Low temperature sintering, structure and electrical properties of BiFeO3-BaTiO3 based piezoelectric ceramics using CuO-B2O3 composite sintering aids

Piezoelectric ceramics usually have high sintering temperature, which cannot meet the low-temperature co-firing requirements of ceramics and metal electrodes in production of micro devices. Here, we studied the effects of CuO-B2O3 binary composite sintering aids on the sintering behavior, phase composition, microstructure, and electrical properties of the bismuth ferrite-barium titanate (0.7BiFeO3-0.3BaTiO3, BFO-BT) based lead-free piezoelectric ceramics. We found that the CuO-B2O3 sintering aids can effectively lower the sintering temperature of the BFO-BT ceramics to 880 ℃, which is far below the melting point of metal electrodes. The BFO-BT based ceramics with 0.5 wt% sintering aids exhibited excellent dielectric, ferroelectric, and piezoelectric properties (εm = 83029, Pm = 38.4 μC/cm2, Pr = 33.8 μC/cm2, d33 = 119 pC/N) with high Curie temperature (TC = 460 ℃). Meanwhile, this ceramic possessed high depolarization temperature (Td) near 300 ℃, demonstrating a good temperature stability of piezoelectricity. This study provides a feasible solution to improve the compatibility of lead-free piezoelectric materials and low-melting point metal electrodes for fabrication of micro piezoelectric devices.