Ultrahigh-temperature piezoelectric polycrystalline ceramics: dramatically enhanced ferroelectricity, piezoelectricity and electrical resistivity in Ca_1−3xBi_2+3xNb_2−xMn_xO₉

Among Aurivillius-phase ferroelectric ceramics, CaBi₂Nb₂O₉ is considered as the best candidate with potential applications in ultrahigh-temperature piezoelectric devices due to the highest T_c (∼940 °C). This paper reports that BiMn co-substitution at A and B sites gives rise to dramatic enchantments in ferroelectricity, piezoelectricity, and electrical resistivity of CaBi₂Nb₂O₉ ceramics. The optimum composition (Ca_0.97Bi_2.03Nb_1.99Mn_0.01O₉) with a T_c of 953 ± 3°C shows a high ferroelectric remnant polarization (P_r), field-induced strain (S₃₃), piezoelectric activity d₃₃ and d^* ₃₃ with values of ∼11.1 µC/cm², 4.9 × 10⁻⁴, 20.8 and 26.1 pC/N, respectively, which are about two to three times those of CaBi₂Nb₂O₉.