Effect of B-site equal-valent doping on ferroelectric properties of SrBi4Ti4O15 ceramics

The structures and properties of Zr and Hf-modified SrBi4Ti4O15（SBTi） ceramics were investigated. We find that the basic crystal structure is not changed after the substitution of equal-valent cations Zr4+ and Hf4+ for the Ti4+ ions at B site in SBTi. Compared with the higher-valent cation doping （V, Nb）, Zr4+ and Hf 4+ substitution can also improve the ferroelectric property of SBTi. The enhancement of remnant polarization （2Pr） by Hf4+ doping is obviously larger than that by Zr4+ doping, though these two cations have almost the same radius. This indicates that the reduced concentration of oxygen vacancy is not the only reason responsible for the improvement of the 2Pr in the B site doping, and other uncertain reasons should also be considered. The piezoelectric properties of these ceramics are investigated briefly. The tendency of piezoelectric constant changing with the doping dosage is nearly consistent with the tendency of 2Pr. Meanwhile, the dielectric properties of these ceramics are investigated, the Curie temperature of the samples varieds slightly with the doping amount, which implies that the good thermal stability of SBTi is not sacrificed.