Water incorporation into the Ba2(In1 − xMx)2O5‪ (M = Sc3+ 0 ≤ x < 0.5 and M = Y3+ 0 ≤ x < 0.35) system and protonic conduction

Ba2(In1 − xMx)2O5 − y / 2(OH)y‪□1 − y / 2 (y ≤ 2; M = Sc3+ 0 ≤ x < 0.5 and M = Y3+ 0 ≤ x < 0.35) compounds were prepared by reacting Ba2(In1 − xMx)2O5‪ phases with water vapor. This reaction is reversible. Analyses of the hydration process by TG and XRD studies show that the thermal stability of hydrated phases increases when x increases and that the incorporation of water is not a single-phase reaction inducing either a crystal system or space group modification. Fully hydrated (y = 2) and dehydrated (y = 0) samples have been stabilized at room temperature and characterized for all compositions. In wet air, all phases show a proton contribution to the total conductivity at temperatures between 350 and 600 °C. At a given temperature, proton conductivity increases with the substitution ratio and reaches at 350 °C, 5.4 10− 3 S cm− 1 for Ba2(In0.65Sc0.35)2O4.2□0.2(OH)1.6.