Zhang Xinping, Tang Fawei, Wang Meng, Zhan Wangbin, Hu Huaxin, Li Yurong, Friend Richard H, Song Xiaoyan
Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124, China.
College of Materials Science and Engineering, Key Laboratory of Advanced Functional Materials, Education Ministry of China, Beijing University of Technology, Beijing 100124, China.
Sci Adv. 2020 Mar 6;6(10):eaax9427. doi: 10.1126/sciadv.aax9427. eCollection 2020 Mar.
Oxygen vacancies often determine the electronic structure of metal oxides, but existing techniques cannot distinguish the oxygen-vacancy sites in the crystal structure. We report here that time-resolved optical spectroscopy can solve this challenge and determine the spatial locations of oxygen vacancies. Using tungsten oxides as examples, we identified the true oxygen-vacancy sites in WO and WO, typical derivatives of WO and determined their fingerprint optoelectronic features. We find that a metastable band with a three-stage evolution dynamics of the excited states is present in WO but is absent in WO. By comparison with model bandstructure calculations, this enables determination of the most closely neighbored oxygen-vacancy pairs in the crystal structure of WO, for which two oxygen vacancies are ortho-positioned to a single W atom as a sole configuration among all O─W bonds. These findings verify the existence of preference rules of oxygen vacancies in metal oxides.
氧空位通常决定金属氧化物的电子结构，但现有技术无法区分晶体结构中的氧空位位置。我们在此报告，时间分辨光谱学可以解决这一挑战并确定氧空位的空间位置。以氧化钨为例，我们确定了WO和WO（WO的典型衍生物）中的真实氧空位位置，并确定了它们的指纹光电特征。我们发现WO中存在具有激发态三阶段演化动力学的亚稳带，而WO中不存在。通过与模型能带结构计算进行比较，这使得能够确定WO晶体结构中最邻近的氧空位对，在所有O─W键中，两个氧空位以单个W原子邻位排列是唯一的构型。这些发现证实了金属氧化物中氧空位偏好规则的存在。
