国际著名应用物理杂志《J. Appl. Phys.》2014年116期的同一期前后篇发表了两篇我院师生在新材料设计及应用上最新学术论文
新材料设计及应用上取得新进展，在国际著名应用物理杂志《J. Appl. Phys.》2014年116期的同一期前后篇，发表了钟克华博士生、黄志高教授等有关栅电极有效功函数，许桂贵老师、黄志高教授等人的磷酸铁锂锂离子正极材料表面修饰的第一性原理计算的研究。
Kehua Zhong(钟克华,博士生), Guigui Xu(许桂贵), Jian-Min Zhang(张健敏) and Zhigao Huang(黄志高), Effects of strain on effective work function for Ni/HfO2 interfaces, J. Appl. Phys. 116(6), 063707 (2014).
ABSTRACT
The effective work functions for Ni/HfO2 interfaces under two strain modes (uniaxial and triaxial strains) were studied by using first-principles methods based on density functional theory. The calculated results indicate that the effective work functions are strongly affected by the type of interface and the strain states (tensile and compressive strains). For the both above strain states, the changed value of the effective work functions linearly increases with increasing strain. Moreover, it is observed that for a certain strain, the variation of the effective work function for triaxial strain state is almost larger than that for uniaxial strain state. Finally, the electrons gas model, the interface dipole, and screening role of HfO2 were used to analyze and explain the strain and interface effects in metal-oxide interfaces. The evident difference between the effective work functions of Ni-Hf and Ni-O interfaces is found to be attributed to different metallic bondings and ionic bondings via the analysis of the charge density distributions. Our work strongly suggests that controlling the strain and interface structure is a promising way for modulating the work function of Ni/HfO2 interfaces.
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Guigui Xu(许桂贵), Kehua Zhong(钟克华,博士生), Jian-Min Zhang(张健敏) and Zhigao Huang(黄志高), First-principles investigation of the electronic and Li-ion diffusion properties of LiFePO4 by sulfur surface modification, J. Appl. Phys. 116(6), 063703 (2014).
ABSTRACT
We present a first-principles calculation for the electronic and Li-ion diffusion properties of the LiFePO4 (010) surface modified by sulfur. The calculated formation energy indicates that the sulfur adsorption on the (010) surface of the LiFePO4 is energetically favored. Sulfur is found to form Fe-S bond with iron. A much narrower band gap (0.67 eV) of the sulfur surface-modified LiFePO4 [S-LiFePO4 (010)] is obtained, indicating the better electronic conductive properties. By the nudged elastic band method, our calculations show that the activation energy of Li ions diffusion along the one-dimensional channel on the surface can be effectively reduced by sulfur surface modification. In addition, the surface diffusion coefficient of S-LiFePO4 (010) is estimated to be about 10−11 (cm2/s) at room temperature, which implies that sulfur modification will give rise to a higher Li ion carrier mobility and enhanced electrochemical performance.
