AI 中文总结
本研究结合实验与第一性原理计算，针对钙钛矿氧化物氧容量预测问题，确定了不同氧化还原机制下的关键描述符，为清洁能源用钙钛矿氧化物的氧容量预测设计提供了理论依据。
AI 中文摘要
钙钛矿氧化物能够可逆地容纳氧化学计量比的大幅变化，使其在化学循环、氧存储等清洁能源技术中具有吸引力。尽管已开展大量优化其氧化还原性质的工作，但能够评估不同组成下氧容量的预测性描述符仍在开发中。本研究结合实验与第一性原理计算，建立了模型钙钛矿系列LnxSr1-xCoO3的组成与氧容量的关系。我们证实，增加Sr2+含量会促进高价Co4+的形成，扩大氧释放过程中可用的阳离子氧化还原库，从而提高氧容量。在该体系中，氧空位形成能可捕捉观测到的趋势，因为氧释放主要由Co4+/Co3+/Co2+氧化还原补偿。然而，在整个稀土系列中，尽管氧空位形成能逐渐降低，氧容量却从La到Lu递减。我们揭示，这种反直觉行为源于一种替代的电荷补偿途径：在氧移除过程中，晶格氧部分被氧化为类O1-物种。重稀土组成（Tb-Lu）通过独特的局部键合环境优先稳定这些氧空穴物种，电荷补偿涉及氧化的晶格氧以及还原的稀土和钴阳离子，因此尽管空位热力学有利，仍会抑制净氧释放。我们进一步确定，当阴离子氧化还原占主导时，由积分晶体轨道哈密顿布居量化的平均金属-氧键强度是氧容量的物理意义明确的描述符。
英文摘要
Perovskite oxides can reversibly accommodate substantial changes in oxygen stoichiometry, making them attractive for clean-energy technologies including chemical looping and oxygen storage. Despite extensive efforts to optimize their redox properties, predictive descriptors capable of assessing oxygen capacity across diverse compositions remain under development. Here, we combine experiments and first-principles calculations to establish composition and oxygen-capacity relationships in the model perovskite series LnxSr1-xCoO3. We confirm that increasing Sr2+ content promotes the formation of high-valence Co4+, expanding the cationic redox reservoir available during oxygen release and thereby enhancing oxygen capacity. In this regime, oxygen-vacancy formation energy captures the observed trend because oxygen release is primarily compensated by Co4+/Co3+/Co2+ redox. Across the rare-earth series, however, oxygen capacity decreases from La to Lu despite progressively lower oxygen-vacancy formation energies. We reveal that this counterintuitive behavior originates from an alternative charge-compensation pathway, in which lattice oxygen is partially oxidized to O1- -like species during oxygen removal. Heavy rare-earth compositions (Tb-Lu) preferentially stabilize these oxygen-hole species through distinct local bonding environments, with charge compensation involving both oxidized lattice oxygen and reduced rare-earth and cobalt cations, thereby suppressing net oxygen release despite favorable vacancy thermodynamics. We further identify average metal-oxygen bond strength, quantified by integrated crystal orbital Hamilton population, as a physically meaningful descriptor for oxygen capacity when anionic redox becomes dominant.
Comments19 pages, 4 figures
