The Synthesis And Properties Of Metal Oxide Nanostructures Through An Oxidation Process

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.