| Silicon nitride(Si3N4) materials have been widely used in metal smelting, aerospace, machining and the like owing to their excellent physical and chemical properties. As one kind of semiconductor material, a wide band gap makes Si3N4 a good matrix material to tailor its band structure by proper doping. One-dimensional nanomaterials have attracted increasing attention because of their unique appearance, excellent performance, and application in the field of micro-nano optoelectronic devices. Therefore, one-dimensional Si3N4 nanomaterials having light emission regulation performance are promising materials for optical and electronic devices operating in harsh environments such as high temperatures, radiation, and strong vibration environments.Based on this background, superfine quartz powder and graphite powder were used as raw materials. They occurred carbothermal reduction nitride(CRN) reaction in nitrogen atmosphere. A large scale of well-crystallized α-Si3N4 nanobelts materials were obtained at the surface of graphite paper under following optimal experiment parameters: temperature of 1550 ℃ for 3h, the nitrogen flow rate of 1 L/min, the graphite paper with Fe(NO3)3. The length of nanobelts was 4-5 mm, and the thickness was about 60 nm. The growth direction was along the [101] axis. Both the VLS base growth and VS tip growth were considered as the main mechanisms for the growth of Si3N4 nanobelts.The micro-area Young’s modulus distribution of Si3N4 nanobelts was measured by an Atomic Force Microscope(AFM) and the average Young’s modulus was approximately 103 GPa. Room temperature photoluminescence properties were tested and three emission peaks at 413, 437, and 462 nm were appeared in the spectrum under the excitation of 365 nm UV light. Their light emission mechanism can be attributed to the defects in Si3N4.Superfine quartz powder, silicon powder, and aluminum powder were used as raw materials to produce the Al-doped Si3N4 nanobelts at the surface of graphite paper under the high temperature and nitrogen atmosphere. The yield and width of nanobelts had the direct relationship with the reaction temperature and the gas concentration.Well crystallizedAl-doped β-Si3N4 nanobelts wereprepared at the graphite paper when the temperature was at 1500 ℃for 3h, the nitrogen flow rate of 1 L/min,and without any metal catalyzer. The longest nanobelts were about 6.9 mm. The width was about 2 um, and the thickness was about 70 nm. The growth direction was along the [100] axis. The growth of Al-doped Si3N4 nanobelts could be explained by VS mechanism.The micro-area Young’s modulus distribution of Al-doped Si3N4 nanobelts was measured by an Atomic Force Microscope(AFM) and the average Young’s modulus was approximately 72 GPa.The light of which wavelength is between 300-400 nm was significantly absorbed by the Al-doped Si3N4 nanobelts. Two intermediate levels of 2.12 eV and 3.10 eV had been introduced between the conduction and valence bands. When the nanobelts were exposed to 365 nm UV excitation, there are three peaks at 418 nm, 439 nm, and 468 nm in the spectrum, which corresponded to original emission peaks of undoped-Si3N4 though slight red shift happened. Their light emission was caused by defect levels in the nanobelts; Otherwise, two strong emission peaks at 400 nm and 580 nm were observed which could be attribute to intermediate levels introduced by Al doping.This work provided an important technology path for the realization of high-quality quartz utilization. Researchoncarbon and silicon thermal reaction laid the theoretical foundation for achieving large-scale production of low-cost silicon nitride nanobelts. Al-doping achieved photoluminescence property regulation of the silicon nitride nanobelts, which further expanded its application scope in the field of solid state light. |
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