Juntong Huang

Fe-catalyzed growth of one-dimensional α-Si3N4 nanostructures and their cathodoluminescence properties.

Preparation of nanomaterials with various morphologies and exploiting their novel physical properties are of vital importance in nanoscientific field. Similarly to the III-N compound semiconductors, Si3N4 nanostructures also could be potentially used for making optoelectronic devices. In this paper, we report on an improved Fe-catalyzed chemical vapour deposition method for synthesizing ultra-long α-Si3N4 nanobelts along with a few nanowires and nanobranches on a carbon felt substrate. The ultra-long α-Si3N4 nanobelts grew via a combined VLS-base and nanobranches via a combined double-stage VLS-base and VS-tip mechanism, as well as nanowires via VLS-tip mechanism. The three individual nanostructures showed variant optical properties as revealed by a cathodoluminescence spectroscopy. A single α-Si3N4 nanobelt or nanobranch gave a strong UV-blue emission band as well as a broad red emission, whereas a single α-Si3N4 nanowire exhibited only a broad UV-blue emission. The results reported would be useful in developing new photoelectric nanodevices with tailorable or tunable properties.

Thermal evaporation synthesis of SiC/SiOx nanochain heterojunctions and their photoluminescence properties

Core–shell SiC/SiOx nanochain heterojunctions have been successfully synthesized on silicon substrate via a simplified thermal evaporation method at 1500 °C without using catalyst, template or flowing gases (Ar, CH4, N2, etc.). X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy and Fourier-transform infrared spectroscopy are used to characterize the phase composition, morphology, and microstructure of the as-synthesized nanostructures. A combined vapor–solid growth and modulation procedure is proposed for the growth mode of the as-grown SiC/SiOx nanochains. The formation of SiOx beads not only relates to the Rayleigh instability and the poor wettability between SiC and SiOx, but also to the existence of a high density of stacking faults within SiC-core nanowires. The photoluminescence spectrum of the nanochains exhibits a significant blue shift, which can be highly valuable for future potential applications in blue-green emitting devices.

Simple growth of BCNO@C core shell fibres and luminescent BCNO tubes

A novel core shell structure (BCNO@C with C core and BCNO shell) has been prepared using a simple heating reaction. These fibres have a diameter around 100–300 nm with lengths up to hundreds of micrometres. To create BCNO@C fibres, the C fibres (cores) were first grown using Ni particle catalysts before adding BCNO shells. Simple burning of the core shell fibres led to the formation of novel B0.43C0.23N0.27O0.07 tubes. Unlike the BCN tubes grown from the substitution of C tubes, the BCNO tubes here have a homogenous structure with luminescence centered at around 386 nm (from 290–700 nm), which was mainly contributed to by the 1,3-B centers, carbene structures and BO2− species. The method used here is suitable to being adapted in the future to tune the electronic structure of BCN based materials.