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Preparation And Photoluminescence Of SiO_x Nanowires And Netlike Nanomaterials By A Kettle Method

Posted on:2008-01-26Degree:MasterType:Thesis
Country:ChinaCandidate:X X LiFull Text:PDF
GTID:2121360242465004Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
The physical limit in microelectronics and demand for rapid signal disposal make the way of signal processing probably changing from electronics to optics. Silicon oxide is a classical insulator and has excellent light-guiding properties. According to photoluminescence research of the silica films and porous silicon oxide, silica is a potential luminescent material which has intensive visible blue light emission. Because of the facts mentioned above, a great effort has been made in the synthesis and luminescence of silicon oxide nano-materials.One-dimensional structure has been became the focus of the silicon oxide research. Up to now, there are some methods to prepare SiOx nanowires. It is necessary for these methods to add metal catalyst and get high temperature and vacuum which make equipments expensive and operation complex. Herein, we have tried to synthesize silicon oxide materials using kettle as equipment. This paper focus on the influences on the growth of SiOx nanowires by a hydrothermal method caused by different reaction conditions such as holding temperature, kettle compactness and holding time. According to the results of the contrast experiments and water behavior at high temperature and pressure, the optimum conditions have been obtained and growth mechanism has been discussed. The preparation of netlike SiOx nanostructure by solvent-thermal approach and its luminescence are put forward in this paper.A mass of SiOx nanowires have been obtained at the optimum condition: 450℃holding temperature, 5% kettle compactness, 6wt% SiO2 powders added in raw materials, 7.5-9.0MPa pressure at holding temperature, 4-10h holding time, 100r/min stirring speed. The smooth SiOx nanowires have uniform distribution in diameter of around 100nm and a length up to several microns. They are only composed of silicon and oxygen with an atomic ratio of 1∶1.16 and have much lower content of oxygen than SiO2. PL spectrum shows that SiOx nanowires have intensive light emission centered at 426nm and 446nm, which can be attributed defect centers arising from oxygen deficiency. Depending on the results of contrast experiments and regulation of hydrothermal method, SiOx nanowires nucleate and grow at the cover of kettle and a V-S mechanism can be utilized to explain their growth. In our experiments, we have gotten a few of special Silicon oxide structures whose growth processes are put forward in this paper. Finally, netlike SiOx nanostructure has been synthesized from ethyl orthosilicate (TEOS) by a two-step method: sol-gel with the hydrolysis of TEOS and solvent-thermal process. The reaction was carried out for 24h at the temperature and pressure of 200℃and 1MPa respectively. The nanorods in the netlike structure have a diameter of about 20nm and a length of 60nm. This material is composed of silicon and oxygen with an atomic ratio of 1∶1.4 and has two states: crystal silicon and amorphous silicon oxide. Intensive blue photoluminescence has been detected in this material and can be observed directly. The gauss fit show that there are two peaks obviously centered at 418nm and 470nm respectively, which is accordant with the oxygen vacancy mechanism. The netlike SiOx has a large number of nanoscale holes and can be used as catalyst carrier after these holes have been filled with catalyst. Thus this structure is probably of interest in integrated optics and catalyst carrier.
Keywords/Search Tags:Hydrothermal method, Solvent-thermal method, Silicon oxide nanowires, netlike SiOx nano-structure, Photoluminescence (PL), Growth mechanism
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