Hydration of acceptor-doped BaSnO3: Implications of the bound states of ionic defects

Abstract The implications of acceptor-bound ionic defects in the hydration of acceptor-doped cubic perovskite BaSnO3 are elucidated based on the thermogravimetric analysis of water uptake and the authors’ recent statistical theory. The oxides BaSn1–xScxO3–δ (0.10 ≤ x ≤ 0.37) and BaSn0.9Sc0.1–xInxO3–δ (x = 0.05, 0.10) were synthesized and experimentally studied. The thermogravimetric measurements showed very good hydration properties of BaSn1–xScxO3–δ: the low-temperature hydrogen concentration was close to the nominal dopant content for all doping levels. The obtained data pertaining to the dopant concentration effect on the hydration isobars are well described by the exploited theory that accounts for the trapping of protons and oxygen vacancies by acceptors. The experimental findings on the effect of scandium substitution with indium on the hydrogen dissolution in the BaSn0.9Sc0.1–xInxO3–δ oxides are also in good agreement with our theoretical predictions. In addition, we discuss the impact of trapping on the hydration enthalpy, entropy and Gibbs free energy of BaSnO3 doped with various acceptors, and establish the type and concentration of acceptor impurities which enhance or inhibit hydration. Our results testify to the pivotal role of the defects’ trapping by acceptors in the hydration of barium stannate, and demonstrate that this effect is important for understanding and prediction of the hydration properties of acceptor-doped perovskites.