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

The Ba 0.985 Ca 0.005 Ti 0.98 Sn 0.02 O 3  +  x mol% MnO 2 (BCTSM x , 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 MnO 2 doping on the phase structure, microstructure, dielectric, ferroelectric and piezoelectric properties of Ba 0.985 Ca 0.005 Ti 0.98 Sn 0.02 O 3 ceramics were investigated systematically. X-ray diffraction patterns revealed that the BCTSM x ceramics are composed of coexisting tetragonal-orthogonal phases. The addition of MnO 2 could significantly improve the sinterability of BCTS ceramics. The BCTSM x ceramics with x  = 0.4 demonstrated an optimum electrical properties: ε r  = 2802, tan δ  = 0.081, T C  = 121 °C, ε max  = 9977, P r  = 11.8 μC/cm 2 , E C  = 2.6 kV/cm, bipolar S max  = 0.25%, unipolar S max  = 0.28%, d * 33  = 1093 pm/V, d 33  = 325 pC/N, k p  = 43.2%, and Q m  = 118.