Catalyst-assisted synthesis and growth mechanism of ultra-long single crystal α-Si3N4 nanobelts with strong violet-blue luminescent properties

Ultra-long single crystal alpha-Si3N4 nanobelts were prepared by thermal chemical vapour deposition (CVD) method. Silicon vapour from the original solid silicon raw material was allowed to react with flowing nitrogen at 1450 degrees C on the carbon felt deposited with Ni(NO3)(2). The as-prepared alpha-Si3N4 nanobelts were 40-60 nm thick, 200-300 nm wide, and up to several millimetres long. Their growth process was governed by the VLS base-growth and the VS tip-growth mechanisms. The former was responsible for the initial nucleation and proto-nanobelt (template) formation of alpha-Si3N4 and the subsequent growth along the [101] or [100] direction, and the latter for the additional growth at the tips. The synergistic function from these two growth mechanisms resulted in the formation of a large quantity of ultra-long alpha-Si3N4 nanobelts. An intense violet-blue visible photoluminescence (PL) of the as-synthesized alpha-Si3N4 nanobelts was observed at room temperature, which could be highly valuable for the future potential applications in optoelectronic nanodevices.