Improved electrical properties in Nb/Fe co-modified CaBi4Ti4O15 high-temperature piezoceramics

Nb/Fe co-doped CaBi4Ti4−x(Nb1/2Fe1/2)xO15(CBT) (x = 0, 0.01, 0.02, 0.025, 0.05, 0.075, and 0.1) high-temperature piezoceramics were synthesized using conventional solid-state reaction method. The effects of Nb/Fe doping level on the structure dielectric, ferroelectric and piezoelectric properties were investigated in detail. It was found that Nb/Fe co-doping effectively improved the electrical performances of CBT ceramic. Significant enhancement of piezoelectric coefficient (d33) was acquired at x = 0.02 with a d33 value of 21.6 pC/N, accompanied by a high Curie temperature (TC) of 793 °C and a low dielectric loss (tanδ) of 5.9% at 400 °C. Moreover, the ceramic showed a good thermal stability with a d33 value of 19.3 pC/N after being annealed at 700 °C for 2 h, keeping 89.4% of its initial value at room temperature. These results indicated great potentials of the Nb/Fe co-doped CBT ceramics for high-temperature piezoelectric applications.