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"The successful creation of both simple and complex
metal-oxide films using PAD is part of the significance of this
invention," said Dean Peterson, director of the Superconductivity
Technology Center. "This technology provides a cost-effective approach
to grow electronic and optical materials, which would find wide
applications in any fields where the material is needed in the film
form."
The PAD process uses a water-based solution to
create a high-quality film of nearly any metal oxide. The films can be
made from a single or several different metals with controlled atomic
weight relationships. Amorphous, polycrystalline, or epitaxial films
can be made with thicknesses from 10 nanometers to hundreds of
nanometers or thicker. Using PAD, Los Alamos researchers have produced
films of simple metal oxides, such as titanium dioxide and zinc oxide,
and also complex metal oxides, such as strontium titanate and indium
tin oxide.
Metal-oxides are emerging as technically important
materials because of the wide variety of physical properties they
possess, which make them attractive for applications such as
photovoltaic devices, gas sensors, microelectronics and corrosion
protection devices. However, the production of high-quality
metal-oxide films with a desired chemical composition has been costly
and challenging. Metal-oxide films are typically grown by physical or
chemical-vapor deposition techniques that require a vacuum system.
Both techniques deliver quality metal-oxide films, but the cost of
deposition systems and the ability to coat films only on a flat
surface have limited their potential applications. Chemical solution
deposition methods, such as sol-gel, are less capital-intensive, but
many metal-oxides cannot be deposited using this technique.
The PAD process distinguishes itself from other
coating technologies because of its low cost and ability to coat large
areas and irregular surfaces. The technique not only uses 100 percent
of the source materials, but also has the capability to control the
chemical phases, microstructures and physical properties of the
materials deposited.
Bill Tumas, director of the Laboratory's Institute
for Hydrogen and Fuel Cell Research said, "Perhaps the most promising
aspect of this new technology is the potential diversity of materials
that can be readily made. PAD has the capability to enable the rapid
exploration of a wide range of new materials."
The development of the PAD metal-oxide film coating
technology involved the expertise of a number of Los Alamos scientists,
including Quanxi Jia, Yuan Lin, Haiyan Wang and Stephen Foltyn from
the Superconductivity Technology Center of the Materials Science and
Technology Division, and Mark McCleskey, Anthony Burrell and Gavin
Collis from the Chemistry Division. The team also included Alexander
DeQuan Li from the Chemistry Department at Washington State University
in Pullman, Wash. |
