(Blacksburg, Va.) -- Virginia Tech's Fiber and Electro-Optics Research Center (FEORC) has received a $9.6 million grant from the Naval Research Laboratory (NRL) for an Optical Sciences Research program.
The five-year research project will focus on optical fiber materials, optoelectronics and fundamental optical materials science related in part to microelectronics, including optical microchips.
Microelectronics is big business in Virginia with the recent announcements by Motorola, IBM/Toshiba and Motorola/Siemens of their intentions to locate multibillion dollar microelectronic fabrication plants in the state. FEORC's research in microelectronics has already shown the possibility of "significant improvements" in the manufacturing of these devices, says Rick Claus, the director of the research center.
NRL's grant follows another huge contract to FEORC, a U.S. Department of the Navy $6.5 million award in March of 1994. Today's award builds and expands upon the 1994 contract when FEORC was asked to look at a whole range of fiber optic applications as they relate to military and commercial uses. This research, some of which remains classified, consisted of three primary components: the production of specialized fibers from improved glass and other materials; the use of optical fibers as sensors; and non-linear optical devices.
The new thrust areas, in addition to the microelectronics-related research, will include high-speed communication waveguide devices and some revolutionary work in the new field of nanostructured materials. These materials, in the form of an alloy such as a metal or a ceramic, are "made of the same atoms as their more common forms, but the atoms are arranged in nanometer-size clusters which become the building blocks of new materials," says Rick Claus, who holds a joint position in the electrical and computer engineering and the materials science engineering departments at Virginia Tech.
Claus and his colleagues, Yanjiing Liu, You-Xiong Wang, and Wei Zhou, have already demonstrated that these new nanomaterials have "remarkable electronic, optical, mechanical and other properties in comparison to larger bulk materials of the same molecular composition." (See article below)
Advantages of using nanoparticles for materials fabrication include the ability to process the materials at low temperatures. Particularly important, say Liu and Claus, is the possibility of forming ultrahard ceramic-like coatings on relatively soft materials at room temperature
FEORC, Virginia's first Center for Innovative Technology's (CIT) Technology Development Center, is home to the country's largest educational fiber optics group. Members of FEORC have submitted more than 100 patent disclosures and published more than 1,000 papers in lightwave technology and applications. FEORC is also currently supported by more than 30 research sponsors.
The following article by Lynn Nystrom describes nanoparticle research:
ENGINEERS TINKER WITH "MOLECULAR LASAGNA"
Building "molecular lasagna" -- that's how researchers in the Fiber & Electro-Optics Research Center (FEORC) at Virginia Tech describe their latest scientific work in nanostructured materials research. The image is intriguing.
Picture a chef in a kitchen using ground beef, noodle and cheese to build the finished entree. If the chef changes the type of cheese from cottage to ricotta or the beef to turkey or to a vegetarian product, the properties of the lasagne can be suited to different tastes. The same thing happens when a researcher builds a material from the nanoparticle stage.
Research staff Yanjing Liu, You-Xiong Wang, Wei Zhou and Rick Claus spend all hours of the day and night in their laboratory experimenting with this next generation of materials.
Engineers and chemists have been playing with advanced synthetic materials known as polymers and composites for several decades now. In the 1980s, material scientists' new buzz word was intelligent or "smart materials." In the mid-1990s, the avant-garde became the creation of nanostructured materials.
Nanostructured materials--in the form of an alloy such as a metal or a ceramic -- "are made of the same atoms as their more common forms, but the atoms are arranged in nanometer-size clusters which become the ....building blocks of the new materials," according to Richard Siegel, a materials engineer at Rennselaer Polytechnic Institute who pioneered these substances in 1985 and wrote about them in a 1996 Scientific American publication.
These new small particles "have remarkable electronic, optical, mechanical and other properties in comparison to larger bulk materials of the same molecular composition," Claus explains. But the trick in making them useful is to collect very large numbers of the nanoclusters and then be able to form them into larger physical systems, with control at the molecular level.
"The idea is that we are making things from the ground up, not the top down. As we build up from the molecular level, we can make things that are smaller, cheaper, and with multiple functions. At the nano level, particles are more energetic," the holder of more than a dozen patents adds.
According to one popular way to make a nanophase material, evaporated atoms are "captured" from a material that is heated beyond its melting point. These atoms are then exposed to an inert gas, such as helium, that will cool them down. The helium takes away the energy of the evaporated atoms and causes them to condense into clusters of anywhere from one to 100 nanometers, according to Siegel's article.
Claus' group instead uses chemical processing methods to both synthesize ultrasmall metal oxide and what he calls "noble metal nanomeatballs," and to coat them with thin polymer passivation layers that "work like meat sauce to keep the particles separated." Agglomeration of the particles reduces the small particle-dominated properties of the material, and makes for the analogy of the nonuniform lasagna taste. FEORC has fabricated multiple ultrasmall molecular clusters with tight size distribution, allowing good engineering design and control over fabricated material properties.
Some advantages of a ceramic made from nanoparticles as opposed to the more traditional form found in a ceramic vase are that they resist breaking and they can be manufactured at room temperature. So, where a jet engine ceramic fan blade once needed to be sintered in a huge oven at the very high temperature of greater than 1500oF, the nanophase material that Claus is developing can be layered in an ordinary room such as in your own home and heated to much lower temperatures.
Claus and his colleagues have devised some ways to build these new building blocks into structures. As he describes the process, they are "using new ionic self-assembled monolayer (ISAM) processing methods to form ultra-small inorganic particles and ultra-thin high-performance buffer layers into near perfect thin-films. We then build up the thickness of the total thin-film, layer by layer."
To the folks who inhabit Silicon Valley, this means that the already tiny microelectronic circuits available today will become even smaller. "The impact over the long term," Claus says, "is that electronic things will become much, much smaller....Currently microelectronic circuits are micron size and nanoparticle is 1000 times smaller than a micro."
Claus even goes so far as to describe the current technology for manufacturing microchips as "brute force." The photolithography technique used to make today's microelectronic circuits is analogous "to digging a strip mine," he says.
On the nano scale, transistors on a microchip would be put together at the molecular level, possibly by the self-assembly methods. In the FEORC nano lab, the trick is to make the molecules assemble into an electronic circuit. And Claus, Liu, and their co-workers have been successful in making their nanoassembled first light emitting diodes.
"Lightning bugs are like slow electronic self-assembled circuits," says Claus. "Our design just tells the molecules where to go, and gets the signals in and out fast." For example, it would greatly speed up the processing of Internet messages.
"A lot of electronics are not that complicated," adds Claus, who holds an endowed professorship.
As he and the FEORC members continue to modify the types of particles, and their long-range structural order in the thin-film, they have manufactured nanomaterials with "surprising" optical transmission, active electronic and optoelectronic properties, abrasion and corrosion resistance, mechanical hardness, and other desirable properties. This is, in part, due to their ability to control particle size, leading to the control over the final material and subsequently, properties of the product.
They have also found that "the incorporation of multiple particles into the same layer, or different layers in a multi-layer film allow control of more than one physical property at the same time," they report.
As the race to custom engineer these nanophase materials continues, FEORC's group has achieved the manufacturing of uniformly sized nanoparticles at the two nanometer dimension as opposed to the broad 10-20 nanometer distributions of nanosized materials typically cited in the literature.
Claus visualizes the "next step" to be the creation of a bucket of nanoparticles that will produce a multipurpose material with the weight of plastic, the electronic flexibility of silicon, and the hardness of kryptonite.
For more information,
contact Lynn Nystrom
540 231 4371 or tansy@vt.edu
or
Professor Richard Claus
540 231 7203 or lmjones@vt.edu