Impact of crystal structure and defect on the electric properties in (LiCeY)-doped CaBi2Nb2O9-based high-temperature piezoceramics

The Ca1-2x(LiCe0.5Y0.5)(x)Bi2Nb2O9 (CBNLCY-100x, x=0-0.07) high-temperature ceramics were prepared by the conventional solid state reaction. The LiCeY substitution at A-site led an improvement of octahedral tilt angle in the a-c plane of CBNLCY-100x ceramics, which resulted in an enhanced piezoelectric constant. CBNLCY-6 ceramic with high Curie temperature (T-C=940 degrees C) had a high piezoelectric coefficient (d(33)) of 16.3 pC/N, even after annealing at 800 degrees C for 2h, the d(33) value of CBNLCY-6 ceramic still remained 92.6% of its original value. Furthermore, the dc conduction mechanism of the ceramics was studied. The oxygen vacancies played an important role in dc conduction mechanism at low temperature and the main conduction mechanism at high temperature was intrinsic conduction. The resistivity of CBNLCY-100x ceramics got highest value at x=0.01 and the resistivity of CBNLCY-1 ceramic enhanced one order of magnitude compared with undoped CaBi2Nb2O9 ceramic. These results suggest that the CBNLCY-6 ceramic is a promising candidate material for ultra-high temperature applications.