Doping effects for high-power piezoelectric properties on Ba(Zr,Ti)O₃–(Ba,Ca)TiO₃-based lead-free piezoelectric ceramics

Abstract

Doping effects of Mn and Cu ions for (1 − x)Ba(Zr_0.2Ti_0.8)O₃–x(Ba_0.7Ca_0.3)TiO₃ [BZT–xBCT] ceramics were investigated with the aim for high-power piezoelectric characteristics such as vibration velocity v_0–p, mechanical quality factor Q_m and piezoelectric constant d₃₁ at large amplitude vibration. The v_0–p is well known as proportional to a product of small signal d₃₁ and Q_m [d₃₁ × Q_m]. BZT–0.6BCT based ceramics were prepared by conventional solid-state reaction method. In the case of CuO doping, both d₃₁ and Q_m values were simultaneously improved by the doping amount of 0.1 wt % to BZT–0.6BCT ceramics, then the d₃₁ × Q_m value was 3 times larger than that of non-doped BZT–0.6BCT ceramics. On contrary to the case of co-doping of CuO and MnCO₃, MnCO₃ 0.6 wt % and CuO 0.1 wt % added BZT–0.6BCT ceramics showed significant improvement of Q_m, then the d₃₁ × Q_m value was approximately 6 times larger than that of non-doped BZT–BCT ceramics. The v_0–p of BZT–0.6BCT ceramics doped with MnCO₃ 1.0 wt % and CuO 0.1 wt % was increased significantly, which was larger than that of Pb(Zr,Ti)O₃-based ceramics. Temperature dependence of v_0–p was also investigated, and it was stable up to 80 °C. It was supposed availability of practical high-power piezoelectric applications at around room temperature.