Superior piezoelectricity and resistivity in CaBi2Nb2O9 high-temperature piezoelectric ceramics: synergy of structural distortion and weak texturing. Issue 42 (18th October 2022) - Pan, Chengbing
Abstract : The polycrystalline CaBi2 Nb2 O9 ceramics with the addition of B2 O3 can realize a large d 33 of 20.4 pC N −1 and an ultra-high electrical resistivity of 1.4 × 10 7 Ω cm (at 600 °C), while still retaining a high T C of 958 °C. Abstract : A high ferroelectric Curie temperature T C, a large piezoelectric coefficient d 33 and resistivity at high temperatures are three virtues that must be considered for piezoelectric materials with potential applications in high temperature sensors. In this paper, the effect of the B2 O3 sintering aid on the microstructural and electrical properties of CaBi2 Nb2 O9 is comprehensively investigated. X-ray and neutron powder diffraction combined with Rietveld refinement demonstrate that a trace amount of B 3+ can be incorporated into the Nb-sites in Nb–O octahedra resulting in an increase in the lattice distortion. The addition of B2 O3 induces the preferential growth of grains along the c -axis, as confirmed by the corresponding (001) pole figure. The enhanced distortion degree of the Nb–O octahedra and microstructural grain orientation give rise to improvements in the ferroelectric and piezoelectric properties of CaBi2 Nb2 O9 . The polycrystalline sample with the addition of 0.25 wt% B2 O3 can realize a large d 33 of 20.4 pC N −1 and an ultra-high electrical resistivity of 1.4 × 10 7 Ω cm (at 600 °C), while still retaining a high T C of 958 °C. These properties are comparable to those of most piezoelectric single crystals used at high temperature. This work provides a cost-effective way to improve the ferroelectric and piezoelectric properties in high temperature piezoelectric ceramics.