Structure and piezoelectric properties of MnO2 doped Ba0.985Ca0.005Ti0.98Sn0.02O3 lead-free ceramics

The Ba0.985Ca0.005Ti0.98Sn0.02O3 + x mol% MnO2 (BCTSMx, x = 0, 0.2, 0.3, 0.4, 0.5 and 0.6) ceramics were fabricated by conventional solid-state reaction method. The effects of MnO2 doping on the phase structure, microstructure, dielectric, ferroelectric and piezoelectric properties of Ba0.985Ca0.005Ti0.98Sn0.02O3 ceramics were investigated systematically. X-ray diffraction patterns revealed that the BCTSMx ceramics are composed of coexisting tetragonal-orthogonal phases. The addition of MnO2 could significantly improve the sinterability of BCTS ceramics. The BCTSMx ceramics with x = 0.4 demonstrated an optimum electrical properties: εr = 2802, tanδ = 0.081, TC = 121 °C, εmax = 9977, Pr = 11.8 μC/cm2, EC = 2.6 kV/cm, bipolar Smax = 0.25%, unipolar Smax = 0.28%, d33* = 1093 pm/V, d33 = 325 pC/N, kp = 43.2%, and Qm = 118.