Piezoelectric softening by Nb substitution in (Ba,Pb)ZrO

Donor doping is commonly applied for softening of the piezoelectric and dielectric properties and facilitation of polarization switching in the ubiquitous Pb(Zr,Ti)O-3 [PZT] ceramics. The origin of the donor-dopant effects is not entirely clear. (Pb,Ba)ZrO3 [PBZ] is a related ferroelectric material, its perovskite A-site being partially occupied by the larger Ba+2 cation, less prone to evaporation than Pb+2, and the B-site is occupied entirely by the valency-stable Zr+4. Here we report on our studies of Nb+5 doping effects in (Pb,Ba)ZrO3. Similarly, to past observations on La+3 and Nb+5 doped PZT, we find a strong reduction in relative density of PBZ when the doping is 0.2% are consistent with Nb+5 entering the B-site and softening effects are observed. The study supports the scenario of hardening due to domain walls pinning by V-Pb-V-O divacancies and softening upon decrease in their concentration.