Two series of manganese-based oxygen storage materials, BaLnMn 2 O 5+δ (Ln = Y, Gd, Nd, and La) and Ca 2 Al 1-x Ga x MnO 5+δ (0 ≤ x ≤ 1), were synthesized and characterized to clarify cationic substitution effects on the oxygen intake/release behaviors of these materials. The thermogravimetric data revealed that the isovalent substitutions neighboring the active sites for oxygen intake/release are very effective. For BaLnMn 2 O 5+δ , fully-reduced δ ≈ 0 products with larger Ln ions showed oxygen intake starting at lower temperatures in flowing O 2 gas, resulting in a systematic relation between the onset temperature and ionic radius of Ln 3+ . Furthermore, the δ vs P(O 2 ) plots at 700 °C indicated a systematic trend: the larger the ionic size of Ln 3+ is, the larger oxygen contents the Ln-products exhibit. For Ca 2 Al 1-x Ga x MnO 5+δ , on the other hand, the temperature-induced oxygen intake/release characteristics appeared to be influenced by Ga-for-Al substitution, where the onset temperatures of oxygen release (upon heating) and oxygen intake (upon cooling) are decreased with increasing the Ga content (x).
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