Molybdenum-substituted Ba2In2O5 as proton conducting electrolyte: structure, water absorption and conductivity

Abstract Effect of molybdenum doping on stabilization of cubic phase, chemical stability and protonic conductivity of barium indate (Ba 2 In 2 O 5 ) has been investigated in this work. Partial substitution of molybdenum for indium, Ba 2 In 2-x Mo x O 5+δ (x = 0.1 to 0.6 and δ = 1.5x), has resulted in stabilization of the Ba 2 In 2 O 5 cubic phase for x = 0.3 and 0.4 compositions. Considering its application as a proton conductor, thermogravimetric experiments have been carried out for moisture pickup evaluation both from stability and protonic conductivity point of view. All of the compositions exhibit an uptake of water below 673 K and also reveal an increase in conductivity with the extent of doping. It is also revealed from the conductivity measurement that activation energy is lowered below 773 K as compared to higher temperature in moist atmosphere which indicated proton conductivity around these temperatures. Graphical abstract