Local structure of lead-containing mixed-ion Perovskite ferroelectrics studied using Neutron total scattering analysis

Abstract

We report the local structures of the lead-containing mixed-ion perovskite Pb(Ni1/32+Nb2/35+)O3 (PNN), Pb(Fe1/23+Nb1/25+)O3 (PFN), and Pb(Zr0.64+Ti0.44+)O3 (PZT) by using a neutron total scattering analysis at low temperatures. Between PNN and PFN, we found that the Pb-O pair distributions were quite similar although they exhibited cubic and monoclinic average structures, respectively. Despite the similarity of the Pb-O pair distributions, the local structures of the B-cations in these compounds were rather different from each other. In the case of PZT, the Pb-O local structure was found to be distinctively different from those of other mixed-valence compounds. These comparisons among Pb-containing mixed-ion perovskites suggest that the valence distribution of the B-cation plays a crucial role in the Pb off-center displacement. Finally, we present the temperature evolution of the Pb-O pair distribution in PNN for temperatures from 300 K to 20 K. Based on this result, we show that a relative displacement of Pb and O against each other is an important feature of the local structure of the Pb ions.