Effect of B-site dopants Nb, Ta and W on microstructure and electrical properties of Ca_(0.85)(Li, Ce)_(0.075)Bi_4Ti_4O_(15)-0.01MnCO_3 piezoelectric ceramics

摘要

(Li, Ce) and Mn modified CaBi_4Ti_4O_(15) (CBT) based ceramics were prepared by the solid state route, and were substituted by the equimolar ions of Nb~(5+), Ta~(5+) and W~(6+) in the B-site. The variations of crystalline structure, microstructure, piezoelectric properties and dielectric properties were investigated. The XRD patterns indicated that all compositions formed a single bismuth layered-structural phase with m = 4. The additions of Nb_2O_5, Ta_2O_5 and WO_3 into CBT-based ceramics were found to affect the electrical properties and temperature stability of the ceramics. Compared with Ta_2O_5 and WO_3, the Nb-substitued ceramics exhibited the optimum piezoelectric property and dielectric property (d_(33) ～ 19.6 pC/N, ε_r ～ 123.7 and tanδ ～ 0.1 %) among all of these samples, together with a high Curie-temperature (T_C ～ 767.6 ℃). Thermally activated depolarization behavior also demonstrated that the Nb~(5+) doped CBT-based ceramics possess outstanding thermal stability of piezoelectric properties. These results indicated that Nb_2O_5 has a substantial effect on the structure and properties of CBT-based ceramics compared to Ta_2O_5 and WO_3.