Abstract
Ultra-long, single crystal, α-Si3N4 nanowires sheathed with amorphous silicon oxide were synthesised by an improved, simplified solid-liquid-solid (SLS) method at 1150 °C without using flowing gases (N2, CH4, Ar, NH3, etc.). Phases, chemical composition, and structural characterisation using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM/HRTEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) showed that the nanowires had Si3N4@SiOx core-shell structures. The growth of the nanowires was governed by the solid-liquid-solid (SLS) mechanism. The room temperature photoluminescence (PL) and cathodoluminescence (CL) spectra showed that the optical properties of the α-Si3N4 nanowires can be changed along with the excitation wavelength or the excitation light source. This work can be useful, not only for simplifying the design and synthesis of Si-related nanostructures, but also for developing new generation nanodevices with changeable photoelectronic properties.
Highlights
Ultra-long, single crystal, α-Si3N4 nanowires sheathed with amorphous silicon oxide were synthesised by an improved, simplified solid-liquid-solid (SLS) method at 1150 °C without using flowing gases (N2, CH4, Ar, NH3, etc.)
We report an improved and simplified SLS method without using flowing gases (N2, CH4, Ar, NH3, etc.) to synthesise α -Si3N4 nanowires at the lower temperature of 1150 °C
The results showed that the PL intensity excited at 254 nm (4.88 eV) was much higher than that excited at 369 nm (3.36 eV), and the peak position was slightly red-shifted with decreasing excitation wavelength
Summary
Ultra-long, single crystal, α-Si3N4 nanowires sheathed with amorphous silicon oxide were synthesised by an improved, simplified solid-liquid-solid (SLS) method at 1150 °C without using flowing gases (N2, CH4, Ar, NH3, etc.). Huo et al.[30] developed a CVD method for the production of single-crystalline α -Si3N4 nanobelts, consisting of the nitridation of a high Si content Fe-Si catalyst by NH3 at 1300 °C. Most of these CVD processes involved complicated equipment, vacuum conditions, and relatively high temperatures. These issues limit the production and application of Si3N4 nanostructured materials. The resulting α -Si3N4 nanowires were structurally characterised and found to have tunable luminescent properties, making them attractive for new optoelectronic applications
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