【作者】 赵烨；

【导师】 张政军；

【作者基本信息】 清华大学 ， 材料科学与工程， 2005， 硕士

【摘要】 纳米结构是指至少有一维空间尺度处于1¹00 nm的结构。与传统块体材料相比,纳米结构具有许多优越的物理、化学性质和更为广泛的应用前景,因此近些年来越来越受到人们的重视。过渡族金属氧化物作为材料中非常重要的一类,在超导、巨磁阻、介电等方面中有很多优异的性质。而纳米尺度的过渡族金属氧化物纳米材料,近些年来在电池、催化剂、电致发光材料、传感器等领域展示出了广阔的应用前景,因此越来越受到人们的重视。如何制备过渡族金属氧化物纳米材料是当今科学界的研究热点之一。在本论文中,使用一种直接氧化金属丝/金属片的方法,在低温下制备出了氧化铌（NbO₂）和氧化镍（NiO）的纳米结构,并且研究了纳米结构生长的机理。其中单相的NbO₂是首次合成,性能测试结果表明NbO₂纳米结构在1 KHz到10 MHz区间内具有良好的介电性质。其介电常数与SiO₂和Si₃N₄相近,且在测试频率范围内稳定,损耗在测试频率范围内始终小于1%,在器件制造中具有良好的应用前景。在制备Ni氧化物纳米结构的过程中,我们分别在Si基底和Ni金属基底上观察到了不同的NiO纳米结构。其中Ni基底生长NiO纳米线的发现提示了我们硅基原位加热金属膜合成纳米线的可能性;而锥形结构的合成对于场发射性能无疑是非常有利的结构。通过对这些结构的表征和不同生长条件的比较,分别研究了其生长机理。这些对于今后其它金属氧化物纳米结构的可控合成是有益的经验。更多还原

【Abstract】 Nanostructures – structures that are defined as having at least onedimension between 1 and 100 nm – have received steadily growing interestsas a result of their peculiar and fascinating properties, and applicationssuperior to their bulk counterparts. Transition metal oxides are a large familyof materials exhibiting various interesting properties such assuperconductivity, colossal magneto-resistance and piezoelectricity, etc.Transition metal oxides with a reduced size down to the nanometer scale arepromising materials for applications in batteries, catalysts, electrochromicmaterials and sensors. The ability to generate such minuscule structures isessential to much of modern science and technology.In this treatise, a simple oxidation process, i.e. heating directly the metalslice or spiral coil, was put forward to fabricate niobium oxide （NbO2） andnickel oxide （NiO） nanostructures. This was the first time the synthesis of pureNbO₂ phase was reported. The NbO₂ nanostructure has excellent dielectricproperties in the frequency range from 1 kHz to 10 MHz. Its dielectric constantis close to those of SiO₂ and Si₃N₄ and independent on the frequency applied.The NbO2 nanostructure has a dielectric loss less than 1% in the measuredfrequency range, which makes it a potential material for applications into MOSdevices.For the synthesis of the nickel oxide nanostructure, it is found thatdifferent NiO nanostructures – nanowires and cones film – were synthesizedon the Si and Ni substrates, respectively. The NiO nanowires synthesized onthe Ni substrate implies the possibility of synthesizing metal oxide nanowiresby heating metal film on the Si/SiO₂ substrate directly, and the cone structuresare advantageous for the field-emission displays. From the nanostructurescharacterization and growth condition comparison, the growth mechanism wasinvestigated, which is useful for the controllable synthesis of other metaloxide nanostructures in the future.更多还原