Electrochemical stability studies by voltammetry on microsamples based on Bi26Mo10O69

The binary oxide Bi26Mo10O69 is the parent compound of a new family of oxygen ion conductors with column type structure. High anion conductivity is observed along the [Bi12O14] columns within the surrounding MoO4 tetrahedra. High conductivity at intermediate temperatures is an important property but the electrochemical stability of the materials plays also an important role for future applications. Since bismuth-based electrolytes turned out to be not stable enough for an application in fuel cells, it is to be assumed that these materials are also easily decomposed. In this work, the decomposition limit was investigated by a voltammetric technique using very small samples. The results show a stability limit located approximately 100 mV more positive than in BIMEVOX. This is probably related to the reduction of Mo(VI) to Mo(IV). No change of oxygen stoichiometry was observed in the Bi26Mo10O69-based material in the course of a voltammogram before the primary reduction process occurs.