Mixed dopant effect in SrZrO3-based proton conductor

The infrared diffuse reflectance spectra in the O–H stretching vibration, νOH, region and the electrical conductivities of Sr(Zr0.92Y0.08 − xScx)O3 − δ and Sr(Zr0.92Y0.08 − xGax)O3 − δ were studied. Whereas the dissolution environment of the proton and the dopant in the terminal compounds was maintained in the Sr(Zr0.92Y0.08 − xScx)O3 − δ, distinctly different proton sites from those in the terminal Sr(Zr0.92Y0.08)O3 − δ and Sr(Zr0.92Ga0.08)O3 − δ appeared in the Sr(Zr0.92Y0.08 − xGax)O3 − δ. The electrical conductivity of the Sr(Zr0.92Y0.08 − xScx)O3 − δ showed a very small increase upon substitution of Y by Sc. The small increase in conductivity for the Sc-doped case was discussed from the viewpoint of proton mobility. For the Sr(Zr0.92Y0.08 − xGax)O3 − δ, the conductivity decreased over an order of magnitude by the substitution of Y by Ga. This decrease in conductivity for the Ga-doped case was attributed to the decrease in the proton concentration.