Papers by Keyword: Bond Energy

Abstract: Inertial Confinement Fusion (ICF) is an effective way to achieve nuclear fusion. In ICF, boron carbide ceramics are a crucial material to prepare targets due to its high neutron capture section, high hardness, and thermal stability. A common way to prepare boron carbide is the precursor transformation method, which can overcome the difficulty in the shaping of ceramics. Decaborane and olefins are reaction materials to prepare the precursor. However, the mechanism of the reaction is not clear now, and few studies on computational chemistry have been published in this area. In this research, the semi-empirical method of quantum mechanics and Molecular Dynamics in Hyperchem8.0 were used to optimize molecules in geometry. Formation enthalpy, bond energy, bond length and angle were calculated to explain experimental patterns. The optimized data is consistent with some typical phenomena in hydroboration and ring-opening metathesis polymerization. It demonstrates that those computational methods in Hyperchem8.0 can be applied to interpret and predict relevant reactions. In addition, this explanation provides a theoretical foundation for future synthesis on polyborane precursor.

Abstract: Material removed by mechanical process inevitably causes surface or subsurface damage containing cracks, plastic scratch, residual stress or dislocations. In nano-abrasive jet polishing (NAJP) the material is removed by chemical impact reaction. The chemical impact reaction is validated by contrast experiment with traditional lap polishing process in which the material is mainly removed through mechanical process. Experiment results show the dependence of the abrasive particles on the choice of materials. Even if the abrasive particle and the workpiece are composed of similar components, the machining properties are remarkably different due to slight differences in their physical properties or crystallography etc. Plastic scratches on the sample which was polished by the traditional mechanical process are completely removed by NAJP process, and the surface root-square-mean roughness has decreased from 1.403nm to 0.611nm. The NAJP process will become a promising method for ultra precision machining method for ultrasmooth optical surface.

Abstract: Chalcogenide glasses are suitable for far-infrared and imaging applications. In the present study, Sb10Se90-xGex (x=0, 19, 21, 23, 25, 27) system has been chosen to study structural transformations via physical parameters. Bulk samples with x = 0, 19, 21, 23, 25 and 27 have been prepared using the melt-quenching technique. A theoretical study of the ternary glass system revealed that there was a significant change in the structural environment of the system due to rigidity percolation, which took place as Se was replaced by Ge, and hence resulted in changes in other physical parameters of the system.

Abstract: We investigated the nucleation of SWNTs and the role of metallic catalyst using firstprinciples calculations. To avoid dangling bonds a closed cap forms on a metal surface. 6 pentagonal rings are introduced into the cap, which reduces the strain energy. A unique tube chirality then grows from the cap, which is controlled by the metal lattice at the nucleation stage. We found that chirality of nanotubes affects the bond energies, including dangling bonds, carbon-carbon bonds & carbonmetal bonds.