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Electronic properties of InAs1-xSbx films with x up to 0.09 have been investigated by reflectance spectra in 1.5-5 eV energy range at room temperature. The real and imaginary parts of the dielectric function were derived by Kramers-Kronig analysis on the reflectance spectra, which show satisfactory agreement with the spectroscopic ellipsometry data. The E1′ and E1′+Δ1′ peaks are attributed to electronic interband transitions at the E1 and E1+Δ1 critical points, respectively. The prominent E2′ peaks, which exhibit high reflectivity and large blueshift, are found to be contributed by hybrid resonance due to the cooperative behavior of both E2-state electrons and plasmons. [ABSTRACT FROM AUTHOR]

Ab initio density functional theory calculations are performed to study the experimentally observed catalytic role of V2O5 in the recycling of hydrogen in magnesium hydride. We find that the Mg–H bond length becomes elongated when MgH2 clusters are positioned on single, two, and three coordinated oxygen sites (O1, O2, and O3) on the V2O5(001) surface. Molecular hydrogen is predicted to spontaneously form at the hole site on the V2O5(001) surface. Additionally, the activation barrier for the dissociation of hydrogen on V-doped Mg(0001) surface is 0.20 eV, which is only 15 of that on pure Mg(0001) surface. Our results indicate that oxygen sites on the V2O5(001) surface and the V dopant in Mg may be important facilitators for dehydrogenation and rehydrogenation, respectively. The understanding gained here will aid in the rational design and development of Mg-based hydrogen storage materials. [ABSTRACT FROM AUTHOR]

Based on a self-similar array model of single-walled carbon nanotubes (SWNTs), the pore structure of SWNT bundles is analyzed and compared with that obtained from the conventional triangular model and adsorption experimental results. In addition to the well known cylindrical endo-cavities and interstitial pores, two types of newly defined pores with diameters of 2–10 and 8–100 nm are proposed, inter-bundle pores and inter-array pores. In particular, the relationship between the packing configuration of SWNTs and their pore structures is systematically investigated. [ABSTRACT FROM AUTHOR]

Based on a self-similar array model, we systematically investigated the axial Young’s modulus (Yaxis) of single-walled carbon nanotube (SWNT) arrays with diameters from nanometer to meter scales by an analytical approach. The results show that the Yaxis of SWNT arrays decreases dramatically with the increases of their hierarchy number (s) and is not sensitive to the specific size and constitution when s is the same, and the specific Young’s modulus Yaxiss is independent of the packing configuration of SWNTs. Our calculations also show that the Yaxis of SWNT arrays with diameters of several micrometers is close to that of commercial high performance carbon fibers (CFs), but the Yaxiss of SWNT arrays is much better than that of high performance CFs. [ABSTRACT FROM AUTHOR]

To describe single-walled carbon nanotube (SWNT) arrays, we propose a self-similar array model. For isolated SWNT bundles, the self-similar array model is consistent with the classical triangular array model; for SWNT bundle arrays, it can present hierarchy structures and specify different array configurations. Based on this self-similar array model, we calculated the energetics of SWNT arrays, investigated the driving force for the formation of macroscopic SWNT arrays, and briefly discussed the hierarchy structures in real macroscopic SWNT arrays. [ABSTRACT FROM AUTHOR]