摘要
Ionic defects, such as oxygen vacancies, play a crucial role in the magnetic and electronic states of transition metal oxides. Control of oxygen vacancy is beneficial to the technological applications, such as catalysis and energy conversion. Here, we investigate the electronic structure of SrCoO3-x as a function of oxygen content(x). We found that the hybridization extent between Co 3d and O 2p increased with the reduction of oxygen vacancies. The valence band maximum of SrCoO2.5+δ has a typical O 2p characteristic. With further increasing oxygen content, the Co ions transform from a high spin Co3+ to an intermediate spin Co4+, resulting in a transition of SrCoO3-x from insulator to metal. Our results on the electronic structure evolution with the oxygen vacancies in SrCoO3-x not only illustrate a spin state transition of Co ions,but also indicate a perspective application in catalysis and energy field.
离子缺陷,比如氧空位,在过渡金属氧化物的磁性和电子结构中起着至关重要的作用.对氧空位进行调控广泛应用于催化和能量转换领域.我们研究了SrCoO3-x的电子结构与氧含量x的关系,发现随着氧空位含量的减少, Co 3d和O 2p之间的杂化增强.SrCoO2.5+δ的价带顶具有明显的O 2p特征.随着氧含量的进一步增加, Co离子从高自旋的Co3+变成了中自旋的Co4+,实现了绝缘体到金属的转变.关于SrCoO3-x中氧空位引起电子结构演变的研究不仅展示了Co离子自旋的转变,同时也为其在催化和能源领域的应用提供了理论支持.
基金
supported by the National Key R&D program of China(2016YFA0401002)
the National Natural Science Foundation of China(11574365,11474349 and 11375228)
