Acceptor doping in the proton conductor SrZrO3

作者：Weston Leigh^*; Janotti A; Cui X Y; Stampfl C; Van de Walle C G

来源：Physical Chemistry Chemical Physics, 2017, 19(18): 11485-11491.

DOI：10.1039/c7cp01471f

Perovskite zirconates such as SrZrO3 exhibit improved proton solubility and conductivity when doped with trivalent cations substituting at the Zr site. In this work, we present a detailed study of Sc and Y dopants in SrZrO3 based on first-principles, hybrid density- functional calculations. When substituting at the Zr site (ScZr, YZr), both dopants give rise to a single, deep acceptor level, where the neutral impurity forms a localized hole polaron state. The epsilon(0/-) charge transition levels are 0.60 eV and 0.58 eV above the valence- band maximum for ScZr and YZr, respectively. Under certain growth conditions, Sc and Y will form self-compensating donor species by substituting at the Sr site (Sc-Sr, Y-Sr), and this is detrimental to proton conductivity. Due to its larger ionic radius, Y exhibits a greater tendency than Sc to self-compensate at the Sr site. We also investigated the proton-dopant association. The binding energy of a proton to a negatively charged acceptor impurity is 0.41 eV for Sc and 0.31 eV for Y, indicating that proton transport is limited by trapping at impurity sites.

• 出版日期2017-5-14