Enhanced piezoelectricity and excellent thermal stabilities in Nb–Mg co-doped CaBi₄Ti₄O₁₅ Aurivillius high Curie temperature ceramics

Nb–Mg co-doped CaBi₄Ti₄O₁₅ ceramics were synthesized for potential high temperature piezoelectric applications via the solid-state reaction technique. The influences of Nb–Mg doping level on structure, piezoelectricity and other electrical properties were systematically researched. The XRD, EDS and Raman scattering results confirmed that the doped Nb–Mg ions had successfully diffused into the crystal lattice of CaBi₄Ti₄O₁₅ ceramic. Co-doping of Nb–Mg enhanced the piezoelectric coefficient d₃₃ effectively without causing significant deterioration on Curie temperature T_C. The CaBi₄Ti_3.9(Nb_2/3Mg_1/3)_0.1O₁₅ ceramic possessed the optimized electric properties with a high d₃₃ value of 24 pC/N accompanied by a high T_C value of 787 °C. In addition, this ceramic also exhibited a good thermal stability with d₃₃ keeping 91% of its original value after annealing at 600 °C. All these results suggested that Nb–Mg co-doped CaBi₄Ti₄O₁₅ ceramic could be a potential candidate for high temperature piezoelectric sensor or detector applications.