Oxygen nonstoichiometry in YBaCo4O7+δ:: Large low-temperature oxygen absorption/desorption capability

An uncommon oxygen absorption/desorption behavior is reported for the cation-stoichiometric cobalt oxide, YBaCo4O7, structurally composed of two kinds of layers of corner-sharing CoO4 tetrahedra. We have found that YBaCo4O7+delta absorbs and desorbs oxygen up to delta approximate to 1.5 in a narrow temperature range below 400 degrees C. The oxygen uptake/release process is highly reversible, being controlled by both temperature and oxygen partial pressure. Such a large low-temperature oxygen-content tunability is of great promise in regard to applications related to, for example, oxygen storage. Materials with similar characteristics are, to a large degree, lacking today.