Crystal structure and proton conductivity in highly oxygen-deficient Ba 1 − x La x (In,Zr,Sn)O 3 − δ perovskites

Results of studies of crystal structure (XRD method with Rietveld analysis), as well as transport properties (AC impedance method in dry and wet Ar atmospheres) are presented in this work for oxygen vacancy-disordered Ba1−xLax(In,Zr,Sn)O3−δ with δ=0.375. La doping in the A-site, as well as Zr or Sn doping in the B-site resulted in stabilization of the cubic Pm–3m perovskite structure for all of the considered materials, despite having high In-content. Systematic studies of the electrical conductivity, performed in the 300–850°C temperature range, allowed discussing the relationship between proton conductivity and structural parameters in the studied compounds. It was found that materials with a larger unit cell parameter possess higher proton conductivity in the whole temperature range, and, at the same time, the proton transference number for these compounds remains higher at higher temperatures.