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Full-Text Articles in Physical Sciences and Mathematics
Structure And Thermophysical Properties Of Single-Wall Si Nanotubes, Xinwei Wang, Zhen Huang, Tao Wang, Yuk Wai Tang, Xiao Cheng Zeng
Structure And Thermophysical Properties Of Single-Wall Si Nanotubes, Xinwei Wang, Zhen Huang, Tao Wang, Yuk Wai Tang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
In this work, molecular dynamics (MD) simulation based on the environment-dependent interatomic potential is carried out to explore the structure, atomic energy distribution, and thermophysical properties of single-wall Si nanotubes (SWSNTs). The unique structure of SWSNTs leads to a wider range energy distribution than crystal Si (c-Si), and results in a bond order in the range of 4.8~5. The thermal conductivity of SWSNTs is much smaller than that of bulk Si, and shows significantly slower change with their characteristic size than that of Si films. Out of the three types of SWSNTs studied in this work, pentagonal SWSNTs have the …
Quantum Confinement Of Crystalline Silicon Nanotubes With Nonuniform Wall Thickness: Implication To Modulation Doping, Binghai Yan, Xiao Cheng Zeng, Jian Wu, Bing-Lin Gu, Wenghui Duan
Quantum Confinement Of Crystalline Silicon Nanotubes With Nonuniform Wall Thickness: Implication To Modulation Doping, Binghai Yan, Xiao Cheng Zeng, Jian Wu, Bing-Lin Gu, Wenghui Duan
Xiao Cheng Zeng Publications
First-principles calculations of crystalline silicon nanotubes (SiNTs) show that nonuniformity in wall thickness can cause sizable variation in the band gap as well as notable shift in the optical absorption spectrum. A unique quantum confinement behavior is observed: the electronic wave functions of the valence band maximum and conduction band minimum are due mainly to atoms located in the thicker side of the tube wall. This is advantageous to spatially separate the doping impurities from the conducting channel in doped SiNTs. Practically, the performance of the SiNT-based transistors may be substantially improved by selective p/n doping in the thinner side …
Thermal Stability Of Nanostructurally Stabilized Zirconium Oxide, Fereydoon Namavar, Gonghua Wang, Chin Li Cheung, Renat F. Sabirianov, Xiao Cheng Zeng, Wai Ning Mei, Jaeil Bai, Joseph R. Brewer, Hani Haider, Kevin L. Garvin
Thermal Stability Of Nanostructurally Stabilized Zirconium Oxide, Fereydoon Namavar, Gonghua Wang, Chin Li Cheung, Renat F. Sabirianov, Xiao Cheng Zeng, Wai Ning Mei, Jaeil Bai, Joseph R. Brewer, Hani Haider, Kevin L. Garvin
Xiao Cheng Zeng Publications
Nanostructurally stabilized zirconium oxide (NSZ) hard transparent films were produced without chemical stabilizers by the ion beam assisted deposition technique (IBAD). A transmission electron microscopy study of the samples produced below 150 °C revealed that these films are composed of zirconium oxide (ZrO2) nanocrystallites of diameters 7.5 ± 2.3 nm. X-ray and selected-area electron diffraction studies suggested that the as-deposited films are consistent with cubic phase ZrO2. Rutherford backscattering spectroscopy (RBS) indicated the formation of stoichiometric ZrO2. The phase identity of these optically transparent NSZ films was in agreement with cubic ZrO2, …
Ab Initio Study Of Hydrogen Adsorption On Benzenoid Linkers In Metal–Organic Framework Materials, Yi Gao, Xiao Cheng Zeng
Ab Initio Study Of Hydrogen Adsorption On Benzenoid Linkers In Metal–Organic Framework Materials, Yi Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We have computed the energies of adsorption of molecular hydrogen on a number of molecular linkers in metal–organic framework solid materials using density functional theory (DFT) and ab initio molecular orbital methods. We find that the hybrid B3LYP (Becke three-parameter Lee–Yang–Parr) DFT method gives a qualitatively incorrect prediction of the hydrogen binding with benzenoid molecular linkers. Both local-density approximation (LDA) and generalized gradient approximation (GGA) DFT methods are inaccurate in predicting the values of hydrogen binding energies, but can give a qualitatively correct prediction of the hydrogen binding. When compared to the more accurate binding- energy results based on the …
Exohedral Silicon Fullerenes: SiNPtN/2 (20≤N≤60), Yong Pei, Yi Gao, Xiao Cheng Zeng
Exohedral Silicon Fullerenes: SiNPtN/2 (20≤N≤60), Yong Pei, Yi Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Using density functional theory method we show that hollow silicon fullerene cages, SiN(20≤N≤60), can be fully stabilized by exohedrally coated platinum atoms (PtN/2), denoted as SiNPtN/2. The exohedral coating PtN/2 passivates the dangling bonds of the silicon cages, thereby making the silicon cages SiN to retain the symmetry and structure of homologous carbon fullerenes CN. In particular, the Ih symmetrical, 60-atom silicon buckminsterfullerene cage (Si60) can be fully stabilized by exohedrally coated 30 Pt atoms. Properties of SiNPtN/2 …
Doping Golden Buckyballs: Cu@Au16- And Cu@Au17- Cluster Anions, Lei-Ming Wang, Satya S. Bulusu, Hua-Jin Zhai, Xiao Cheng Zeng, Wang
Doping Golden Buckyballs: Cu@Au16- And Cu@Au17- Cluster Anions, Lei-Ming Wang, Satya S. Bulusu, Hua-Jin Zhai, Xiao Cheng Zeng, Wang
Xiao Cheng Zeng Publications
The discovery of the unique catalytic effects of gold nanoparticles on oxide substrates[1] has stimulated a flurry of research into the structures and properties of free gold nanoclusters, which may hold the key to elucidating the catalytic mechanisms of supported gold clusters. One of the most remarkable results has been the discovery of planar gold cluster anions (Aun-) of up to twelve gold atoms and the 2D to 3D transition for clusters with n larger than 12.[2]– [4] Among larger gold clusters, Au20 has been found to be a perfect tetrahedron.[5] A more recent study of …
Molecular Dynamics Of Homogeneous Nucleation In The Vapor Phase Of Lennard-Jones. Iii. Effect Of Carrier Gas Pressure, Kenji Yasuoka, Xiao Cheng Zeng
Molecular Dynamics Of Homogeneous Nucleation In The Vapor Phase Of Lennard-Jones. Iii. Effect Of Carrier Gas Pressure, Kenji Yasuoka, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A molecular dynamics simulation of vapor phase nucleation has been performed with 40 000 Lennard-Jones particles for the target gas and 0–160 000 particles for the carrier gas. Three carrier gas models are adopted, including a soft-core model, a Lennard-Jones model, and a modified Lennard-Jones model in which the attractive interaction can be adjusted. The effect of the carrier-gas pressure is assessed through computing and comparing the rate of nucleation and cluster size distribution. It is found that the effect of the carrier-gas pressure can be strongly dependent on the carrier-gas model. A positive effect _enhancement of the nucleation rate_ …
Hydrogen Storage In Pillared Li-Dispersed Boron Carbide Nanotubes, Xiaojun Wu, Yi Gao, Xiao Cheng Zeng
Hydrogen Storage In Pillared Li-Dispersed Boron Carbide Nanotubes, Xiaojun Wu, Yi Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Ab initio density-functional theory study suggests that pillared Li-dispersed boron carbide nanotubes is capable of storing hydrogen with a mass density higher than 6.0 weight% and a volumetric density higher than 45 g/L. The boron substitution in carbon nanotube greatly enhances the binding energy of Li atom to the nanotube, and this binding energy (~ 2.7 eV) is greater than the cohesive energy of lithium metal (~1.7 eV), preventing lithium from aggregation (or segregation) at high lithium doping concentration. The adsorption energy of hydrogen on the Li-dispersed boron carbide nanotube is in the range of 10 – 24 kJ/mol, suitable …