Novel polymeric phases proposed by cold-pressing SiC tubes

Abstract

A detailed structural evolution behavior of SiC SWNTs under high-pressure is studied by using density functional theory (DFT). We proposed four new polymeric phases (hP4-SiC, hP48-SiC, oI32-SiC and oA40-SiC), which possess the high stability, outstanding electronic and mechanical properties. The hP4-SiC, hP48-SiC and oA40-SiC are indirect band gap semiconductors, while the oI32-SiC is direct band gap semiconductor. The exhibited suitable band gap (~ 3.1 eV) allows hP4-SiC, hP48-SiC, oI32-SiC and oA40-SiC as the potential blue-laser diodes materials. The Si-C bond in four new structures is the strong covalent bond in sp3 hybridization, which results in their high stability and high hardness. The exhibited high decomposition temperature and high hardness make them as the potential high temperature abrasive materials. The stacking way of different rings in structures and atomic arrangement configurations of C and Si atoms in rings induce the anisotropic stiffness of polymeric structures. The analysis of XRD, Raman and IR spectra is performed for a guideline of their synthesis in experiment. These results would help to understand the structural evolution of SiC SWNTs under high pressure while contribute to develop the high hardness and high temperature devices.

Epitaxial growth and structural properties of silicene and other 2D allotropes of Si

“…Recently, the adsorption at 200 K of potassium atoms has been studied on the silicene (3 × 3)/Ag (4 × 4) reconstruction. 197 Whereas K atoms form a dispersed phase at low coverage, they organize into a close-packed layer for a coverage of about 0.17 ML. From STM observations, it was found that the lattice constant of the ordered K layer is the same as the silicene one, while DFT computations indicated that K atoms adsorb on bridge sites, leading to the formation of three different domains equivalent per rotational symmetry (see Fig.…”