Synthesis, thermal stability, and oxygen intake/release characteristics of YBa(Co1−xAlx)4O7+δ

The YBaCo4O7+d (Y-114) phase has recently attracted interests as a potential oxygen storagematerial due to its oxygen intake/release capability at 200–400 8C. Nevertheless, thermal instability of Y-114 has been an obstacle for future applications, since this compound immediately starts to decompose when the sample is heated at 700–800 8C in oxygen-rich atmosphere. Here we demonstrate that Al-for-Co substitution in Y-114 drastically enhances the thermal stability. Substituting only 10 at.% of aluminum for cobalt in Y-114 essentially suppresses the decomposition reaction seen at 700–800 8C, while well retaining its remarkable oxygen intake/release capability at 200–400 8C. It is also revealed that the addition of aluminum effectively reduces the particle size. The Al-substituted Y-114 products exhibit superior oxygen intake/release response to the Al-free products upon switching the atmosphere between O2 and N2.