The effect of B-site (W/Nb) co-substituting on the electrical properties of sodium bismuth titanate high temperature piezoceramics

The effect of (W/Nb) co-doping at the B-site on the properties of Na0.5Bi4.5Ti4O15-based ceramics was systematically investigated in first. The distortion of lattice caused by B-site substitution improved piezoelectric activity greatly. With the introduction of W/Nb doping, these activation energy parameters indicate the existence of the p-type electrical conductivity and the oxygen vacancies motion. The oxygen vacancy migration may be suppressed because of the oxygen ion mobility being affected by the W/Nb doping, but at last the electron carriers may play an important role with the increase of electron concentration and lattice distortion. The piezoelectric coefficient d33 of the (W/Nb) co-substituted samples is 28 pC/N, more than 2.5 times as much as the d33 value of the pure Na0.5Bi4.5Ti4O15 ceramics (∼11 pC/N). Decreasing with modification, the dielectric loss of x = 0.020 sample is only 0.33%. Meanwhile, the thickness coupling factor kt, the planar coupling factor kp and the mechanical quality factor Q are 28.0%, 7.0% and 2471, respectively. Together with its high Tc (∼645 °C), the dielectric and piezoelectric properties of doped sample exhibiting a very stable temperature behavior make the (W/Nb) co-substituted Na0.5Bi4.5Ti4O15-based ceramics a promising candidate for high temperature applications.