Microstructures of the silicon carbide nanowires obtained by annealing the mechanically-alloyed amorphous powders

摘要

Silicon, graphite and boron nitride powders were mechanically alloyed for 40 h in argon. The as-milled powders were annealed at 1700 degrees C in nitrogen for 30 min. The annealed powders are covered by a thick layer of gray green SiC nanowires, which are 300 nm to 1000 nm in diameter and several hundred microns in length. Trace iron in the raw powders acts as a catalyst, promoting the V-L-S process. It follows that the actual substances contributing to the growth of the SiC nanowires may be silicon, graphite and the metal impurities in the raw powders. The results from HRTEM and XRD reveal that the products contain both straight alpha/beta-SiC nanowires and nodular alpha/beta-SiC nanochains. It is interestingly found that 6H-SiC coexists with 3C-SiC in one nodular nanowire. This novel structure may introduce periodic potential field along the longitudinal direction of the nanowires, and may find applications in the highly integrated optoelectronic devices. (C) 2015 Elsevier Inc. All rights reserved.