High temperature dielectric, ferroelectric and piezoelectric properties of Mn-modified BiFeO3-BaTiO3 lead-free ceramics

Lead-free and high-temperature 0.71BiFeO3-0.29BaTiO3 ceramics with Mn modification (BF-BT-x %Mn) were fabricated by conventional solid-state reaction method, and the high temperature dielectric, ferroelectric and piezoelectric properties were investigated. All compositions exhibited pseudo-cubic phases. Mn modification improved the electrical properties of BF-BT solid solutions at both room and high temperature. The Curie temperature T C, depolarization temperature T d, dielectric constant e r, dielectric loss tanδ, piezoelectric constant d 33, electromechanical coupling factor k p, remnant polarization P r of BF-BT-1.2 %Mn ceramics were 506, 500 °C, 556, 0.04, 169 pC N−1, 0.373, 31.4 μC cm−2, respectively. The e r, tanδ, and k p of BF-BT-1.2 %Mn ceramics were stable with the increase of temperature until 500 °C. The coercive field E c of BF-BT-1.2 %Mn ceramics was nearly 30 kV cm−1 at 200 °C, which was much larger than those of PZT, BS-PT,BNT and KNN ceramics. The high field strain coefficient d*33 reached as large as 525 pm V−1 at 200 °C. These results showed that the BF-BT-x %Mn ceramics were promising candidate for high temperature piezoelectric applications.