Protonic conductor Lu–doped BaSnO3: Lutetium solubility, electrical properties and H/D effects.

Recently it was found that doped barium stannates have proton conductivity and can be used for various electrochemical applications. In this study, we investigated the effect of lutetium doping of the tin sublattice on the functional performance of oxides BaSn 1-х Lu х O 3 (х = 0, 0.05, 0.1, 0.15). Oxides with the concentration of lutetium up to 10% mol. were found to be single-phase, crystallizing in a cubic structure with a space group Pm 3 m. The lattice parameter increases linearly with the concentration of lutetium. The oxide with 15 % mol. of lutetium contains an additional phase of Lu 2 Sn 2 O 7. Electrical conductivity of the oxides was studied by the 4-probe DC method and impedance spectroscopy. Experiments were carried out in H 2 O and D 2 O - containing air atmospheres, as well as under dry air conditions. It was found that electrical conductivity of BaSnO 3 does not depend on humidity, while for Lu-doped oxides tends to decrease with increase in the humidity. Impedance data analysis has shown that change in the humidity mostly affects the grain boundary resistance. It is shown for the first time that the conductivity of BaSn 1-х Lu х O 3-δ in D 2 O-containing air is higher than in H 2 O-containing air, which was explained by the thermodynamic isotope effect. [ABSTRACT FROM AUTHOR]