US Patent Number
A method of producing networks of low melting metal oxides such as crystalline gallium oxide comprised of one-dimensional nanostructures. Because of the unique arrangement of wires, these crystalline networks defined as “nanowebs”, “nanowire networks”, and/or “two-dimensional nanowires”. Nanowebs contain wire densities on the order of 109/cm2. A possible mechanism for the fast self-assembly of crystalline metal oxide nanowires involves multiple nucleation and coalescence via oxidation-reduction reactions at the molecular level. The preferential growth of nanowires parallel to the substrate enables them to coalesce into regular polygonal networks. The individual segments of the polygonal network consist of both nanowires and nanotubules of β-gallium oxide. The synthesis of highly crystalline noncatalytic low melting metals such as β-gallium oxide tubes, nanowires, and nanopaintbrushes is accomplished using molten gallium and microwave plasma containing a mixture of monoatomic oxygen and hydrogen. Gallium oxide nanowires were 20-100 nm thick and tens to hundreds of microns long. Transmission electron microscopy (TEM) revealed the nanowires to be highly crystalline and devoid of any structural defects. Results showed that multiple nucleation and growth of gallium oxide nanostructures can occur directly out of molten gallium exposed to appropriate composition of hydrogen and oxygen in the gas phase. The method of producing nanowebs is extendible to other low melting metals and their oxides such as for example: zinc oxide, tin oxide, aluminum oxide, bismuth oxide, and titanium dioxide.
University of Kentucky Research Foundation, Lexington, KY (US), University of Louisville, Louisville KY (US)
Sunkara, Mahendra; Sharma, Shashank; Davis, Burt H.; and Graham, Uschi M., "Formation of Metal Oxide Nanowire Networks (Nanowebs) of Low-Melting Metals" (2008). Center for Applied Energy Research Faculty Patents. Paper 12.