【作者】 胡波；

【导师】 麦立强；

【作者基本信息】 武汉理工大学 ， 材料学， 2008， 硕士

【摘要】 一维纳米材料因为具有显著的各向异性结构和固有的量子限域效应而产生许多优异的物化性能,引起了广大学者的研究兴趣。银钒氧化物由于存在银和钒特殊的氧化态而具有优良的电化学性能、磁性能及电输运特性,可应用于心脏起搏器电池材料、电子自旋器件、敏感器件等方面。本论文以具有带状质点的V₂O₅溶胶为钒源,采用流变相自组装法制备了银钒氧化物一维纳米材料,并用XRD、SEM、TEM、EDS、SAED等手段对产物进行表征,讨论了合成工艺参数对产物结构和形貌的影响。通过组装基于粉末AgVO₃纳米棒材料和单根AgVO₃纳米棒的气敏传感器件,研究了该材料的气敏性能。得到的主要结果和结论如下:1.得到的产物为长几到数十微米,直径100～400nm的纳米纤维聚集成的束状β-AgVO₃,该纳米纤维是由直径为数纳米至50nm左右的Ag纳米颗粒所包覆的AgVO₃纳米棒构成,纳米棒的直径为40～100nm。2.升高水热反应温度和延长反应时间均有利于AgVO₃准一维纳米材料的形成,但当反应时间过长时,晶粒的择优取向生长变弱,产物逐渐生长为微米级的块状结构。搅拌和超声处理使固体反应物Ag₂O充分、均匀进入到V₂O₅溶胶层间,使反应在较低温度下就可以进行。3.在由粉末AgVO₃纳米棒所制备的气敏器件中,样品在不同的加热电压下对乙醇气体均具有敏感特性。乙醇与AgVO₃纳米材料表面从空气中吸附的氧形成的氧负离子发生反应,从而将捕获的电子释放,而使材料的电阻减小。4.由Ag纳米颗粒包覆的单根AgVO₃纳米棒气敏器件,在0.1V电压下,300℃时,Ar气氛中对甲烷气体具有好的敏感特性,最低响应浓度为50ppm。CH₄能够分解出甲基自由基CH₃和H·自由基,两个甲基自由基和纳米棒表面的晶格氧以及H·通过一系列的反应最终生成C₂H₄,、H₂O以及一个氧空位,氧空位能参与导电从而使纳米棒的电阻减小。并且两个H·自由基也能与纳米棒表面的晶格氧反应生成水,而产生一个氧空位,使得纳米棒的电阻减小。此外,纳米棒表面所包覆的Ag纳米颗粒,有可以促进CH₄的分解反应在低温下进行。更多还原

【Abstract】 In recent years,great attention has been focused on one dimentional nanostructured materials due to the excellent physical and chemical properties. Silver vanadium oxide was applied as anode material in primary batteries,electron spin device and the sensitive device because of good electrochemical,magnetic and electronic transport properties.In the present work,silver vanadium oxide nanomaterials were successfully assembled by ultrasonic treatment followed by rheological self-assembling methods using V₂O₅ sol.The products obtained were analyzed by XRD,SEM,TEM,EDS and SAED.The parameters of the reaction and the growing mechanism were discussed.The gas sensing property and mechanism of bulk AgVO₃ nanomaterials and single AgVO₃ nanorod were also studied.The main conclusions are as follows:1.The obtainedβ-AgVO₃ nanomaterials with the length from several to several tens micrometers form bundles of agglomerated smaller filaments with diameters ranging from 100 to 400 nm.This nanostructure is made up of nanorods with the diameters of 40～100nm coated by Ag nanospheres with diameters of several nanometers to 50nm.2.The increases of hydrothermal temperature and time are helpful to formation of one dimensional nanostrcutres,but the microscale lamella structure will be attained because of the weakening of anisotropic growth when the time exceeds certain values.Stirring and ultrasonic treatment can make Ag₂O particles enter the interlayer of V₂O₅ sol easily and uniformly,resulting in the occurrence of reaction in lower temperature.3.The bulk AgVO₃ nanorods obtained have gas sensing property to ethanol gas. The ethanol gas can react with the negatively charged oxygen adsorbates,and release a trapped electrons at the same time.These electrons can reduce the resistance of the gas sensor.4.The single AgVO₃ nanorod has gas sensing property to methane gas under 0.1V, 300℃in Ar atmosphere with low response concentration of 50 ppm.The methane can dissociates to a methyl group and hydrogen,two hydrogen can react with a lattice oxygen on the surface and produce water and an oxygen vacancy.These oxygen vacancies can reduce the resistance.And two methyl group,a hydrogen can react with a lattice oxygen on the surface,which can produce an oxygen vacancy too. It also enhance the conductivity of the nanorods.Moreover,the Ag on the surface of the nanorods could be helpful to the decomposition reaction of CH₄ at low temperature.更多还原