Chang-Ying Wang
Chinese Academy of Sciences
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Featured researches published by Chang-Ying Wang.
Materials | 2017
Hui Wang; Han Han; Gen Yin; Chang-Ying Wang; Yu-Yang Hou; Jun Tang; Jianxing Dai; Cuilan Ren; Wei Zhang; Ping Huai
MAX phase materials have attracted increased attention due to their unique combination of ceramic and metallic properties. In this study, the properties of vacancies in Ti3AlC2 and Ti3SiC2, which are two of the most widely studied MAX phases, were investigated using first-principles calculations. Our calculations indicate that the stabilities of vacancies in Ti3SiC2 and Ti3AlC2 differ greatly from those previously reported for Cr2AlC. The order of the formation energies of vacancies is VTi(a) > VTi(b) > VC > VA for both Ti3SiC2 and Ti3AlC2. Although the diffusion barriers for Ti3SiC2 and Ti3AlC2 are similar (~0.95 eV), the properties of their vacancies are significantly different. Our results show that the vacancy–vacancy interaction is attractive in Ti3AlC2 but repulsive in Ti3SiC2. The introduction of VTi and VC vacancies results in the lattice constant c along the [0001] direction increasing for both Ti3SiC2 and Ti3AlC2. In contrast, the lattice constant c decreases significantly when VA are introduced. The different effect of VA on the lattice constants is explained by enhanced interactions of nearby Ti layers.
Molecular Physics | 2015
Chang-Ying Wang; Cheng Cheng; Jing Su; Ping Huai
The knowledge of chemical bonding for actinide fluoride compounds is essential to understand and predict the physical and chemical behaviour of actinide elements in fluoride molten salt. In this work, the bonding nature of actinide tetrafluorides AnF4 (An = Th−Cm) is investigated by using scalar relativistic density functional theory. Bond order analyses show relatively stronger An–F bonds for An = U−Np and weaker ones for An = Th, Am, and Cm. Despite the dominant ionic character of An–F bonds, a considerable covalent interaction is indicated by the overlap integral value of F 2p and actinide 5f, 6d orbitals. Both natural population analyses and electron density analyses show that An–F covalency rises initially before reducing in the latter systems with the maximum at Np and Pu and the obviously strong ionic bonding character in An = Th, Am, and Cm. Compared to AnCp4 (Cp = η5–C5H5) reported in the literature, our study on AnF4 suggests a much more prominent actinide–ligand covalent interaction. And the roles of orbital overlap and near-degeneracy in driving covalency are discussed.
Scientific Reports | 2017
Yongliang Guo; Cun Yu; Jun Lin; Chang-Ying Wang; Cuilan Ren; Baoxing Sun; Ping Huai; Ruobing Xie; Xuezhi Ke; Zhiyuan Zhu; Hongjie Xu
Thorium-carbon systems have been thought as promising nuclear fuel for Generation IV reactors which require high-burnup and safe nuclear fuel. Existing knowledge on thorium carbides under extreme condition remains insufficient and some is controversial due to limited studies. Here we systematically predict all stable structures of thorium dicarbide (ThC2) under the pressure ranging from ambient to 300 GPa by merging ab initio total energy calculations and unbiased structure searching method, which are in sequence of C2/c, C2/m, Cmmm, Immm and P6/mmm phases. Among these phases, the C2/m is successfully observed for the first time via in situ synchrotron XRD measurements, which exhibits an excellent structural correspondence to our theoretical predictions. The transition sequence and the critical pressures are predicted. The calculated results also reveal the polymerization behaviors of the carbon atoms and the corresponding characteristic C-C bonding under various pressures. Our work provides key information on the fundamental material behavior and insights into the underlying mechanisms that lay the foundation for further exploration and application of ThC2.
Communications in Theoretical Physics | 2018
Chang-Ying Wang; Yongliang Guo; Yuanyuan Zhao; Guangli Zeng; Wei Zhang; Cuilan Ren; Han Han; Ping Huai
Within the framework of density functional theory calculations, the structural, vibrational, and electronic properties of Zrn Cn − 1 (n = 2, 3, and 4) and their functionalized MXenes have been investigated. We find that the most stable configurations for Zr-C MXene are the ones that the terminal groups F, O, and OH locate on the common hollow site of the superficial Zr layer and its adjacent C layer. F and OH-terminated Zr3 C2 and Zr4 C3 have small imaginary acoustic phonon branches around Γ point while the others have no negative phonon modes. The pristine MXenes (Zr2 C, Zr3 C2 and Zr4 C3 ) are all metallic with large DOS contributed by the Zr atom at the Fermi energy. When functionalized by F, O and OH, new hybridization states appear and the DOS at the Fermi level are reduced. Moreover, we find that their metallic characteristic increases with an increase in n. For (Zrn Cn − 1 )O2, Zr2 CO2 is a semiconductor, Zr3C2O2 is a semimetal, and Zr4 C3O2 becomes a metal.
Chinese Physics B | 2016
Cheng Cheng; Han Han; Cuilan Ren; Chang-Ying Wang; Kuan Shao; Ping Huai
The first principles density-functional theoretical calculations of U adatom adsorption and diffusion on a planar graphene and quasi-one-dimensional graphene nanoribbons (GNRs) are performed. An energetic preference is found for U adatom diffusing to the hollow sites of both graphene and GNRs surface. A number of U distinctive diffusion paths either perpendicular or parallel to the ribbon growth direction are examined. The edge effects are evidenced by the calculated energy barriers of U adatom diffusion on armchair and zigzag nanoribbons surfaces. The calculation results indicate that the diffusion of U adatom from the inner site toward the edge site is a feasible process, particularly in zigzag GNR. It is viable to control the initial morphology of nuclear carbon material to retard the diffusion and concentration of nuclides.
Journal of Nuclear Materials | 2017
Kuan Shao; Han Han; Wei Zhang; Hui Wang; Chang-Ying Wang; Yongliang Guo; Cuilan Ren; Ping Huai
Physical Review B | 2016
Yongliang Guo; Chang-Ying Wang; Wujie Qiu; Xuezhi Ke; Ping Huai; Cheng Cheng; Zhiyuan Zhu; Changfeng Chen
Chinese Physics B | 2017
Kuan Shao; Han Han; Wei Zhang; Chang-Ying Wang; Yongliang Guo; Cuilan Ren; Ping Huai
Procedia Chemistry | 2012
Cheng Cheng; Chang-Ying Wang; Ping Huai; Zhi-Yuan Zhu
Computational Materials Science | 2017
Kuan Shao; Han Han; Wei Zhang; Hui Wang; Chang-Ying Wang; Yongliang Guo; Cuilan Ren; Ping Huai