Xie Wei, Lee Yueh-Lin, Shao-Horn Yang, Morgan Dane
Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
Electrochemical Energy Laboratory, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
J Phys Chem Lett. 2016 May 19;7(10):1939-44. doi: 10.1021/acs.jpclett.6b00739. Epub 2016 May 11.
Stability of oxygen point defects in Ruddlesden-Popper oxides (La1-xSrx)2MO4±δ (M = Co, Ni, Cu) is studied with density functional theory calculations to determine their stable sites, charge states, and energetics as functions of Sr content (x), transition metal (M), and defect concentration (δ). We demonstrate that the dominant O point defects can change between oxide interstitials, peroxide interstitials, and vacancies. In general, increasing x and atomic number of M stabilizes peroxide over oxide interstitials as well as vacancies over both peroxide and oxide interstitials; increasing δ destabilizes both oxide interstitials and vacancies but barely affects peroxide interstitials. We also demonstrate that the O 2p-band center is a powerful descriptor for these materials and correlates linearly with the formation energy of all defects. The trends of formation energy versus x, M, and δ and the correlation with O 2p-band center are explained in terms of oxidation chemistry and electronic structure.
利用密度泛函理论计算研究了Ruddlesden-Popper氧化物(La1-xSrx)2MO4±δ（M = Co、Ni、Cu）中氧点缺陷的稳定性，以确定其稳定位置、电荷状态以及作为Sr含量（x）、过渡金属（M）和缺陷浓度（δ）函数的能量学。我们证明，主要的氧点缺陷可以在氧化物间隙、过氧化物间隙和空位之间变化。一般来说，增加x和M的原子序数会使过氧化物比氧化物间隙更稳定，同时使空位比过氧化物和氧化物间隙都更稳定；增加δ会使氧化物间隙和空位都不稳定，但对过氧化物间隙几乎没有影响。我们还证明，O 2p带中心是这些材料的一个有力描述符，并且与所有缺陷的形成能呈线性相关。根据氧化化学和电子结构解释了形成能随x、M和δ的变化趋势以及与O 2p带中心的相关性。
