Microstructure and electrical properties of Nb and Mn co-doped CaBi4Ti4O15 high temperature piezoceramics obtained by two-step sintering
Bismuth layer structural ceramics with a composition of CaBi4Ti3.95Nb0.05O15+0.2 wt% MnO2 (CBTN-Mn) were prepared by a two-step sintering (TSS) approach. The effect of sintering process on the microstructure and its relationship with the electrical properties of the CBTN-Mn ceramics was investigated. A dense microstructure with small and homogeneous grains was obtained under an optimized two-step sintering condition, leading to a strongly enhanced piezoelectric constant (d33=27 pC/N). In addition, this ceramic also possesses high Curie temperature (Tc=790 °C), low dielectric loss (tan δ=0.2%) and high dc resistivity (ρ=5.5x106 Ω cm at 500 °C), indicating its potential for high temperature piezoelectric sensing applications.