Troy Barbee
Father of "Atomic Engineering"
February / March 06
Volume 4 Number 1
Troy W. Barbee Jr. spent part of his youth knocking heads on the football gridiron and rugby pitch, but he found his true calling on a much smaller playing field.
A senior materials scientist at Lawrence Livermore National Laboratory, Barbee is a pioneer in the now hot new field of nanotechnology in which scientists manipulate materials a few atoms at a time.
In the mid-1970s, as laboratory director of the Center for Materials Research at Stanford University, Barbee wrote one of the first papers describing what he termed "atomic engineering in its infancy." Since then he has been working to perfect and apply the technique to the creation of unique multilayer materials with properties that can't be found in nature.
"I realized very early on that I could walk into a lab any day of the week and choose to make something nobody else had ever made," Barbee says. "That's very exciting—€”but it's even better if you have a goal in mind."
Among the goals Barbee's multilayer materials have already reached:
—€ Advanced multilayer optics that provided the first detailed pictures of the sun's magnetic corona, and are now enabling the creation of the next generation of ground- and space-based telescopes, computer chips and hard disk drives
—€ Diagnostic tools and control systems that support the development of the world's most powerful lasers and the reliability of the nation's nuclear weapons stockpile
—€ X-ray interferometers to study colliding plasmas, essential in the development of nuclear fusion and its promise of unlimited energy
—€ Revolutionary "NanoFoil®" technology that can solder heat-sensitive materials at low temperatures.
"Troy's passion for creating new materials technologies is intoxicating," says Timothy Weihs, a former Livermore postdoctoral researcher in Barbee's laboratory who went on to help found the company that developed NanoFoil. "He can fill a room with his enthusiasm and his drive. He's simply very gifted at making new materials."
Multilayer materials are like tiny Dagwood sandwiches. They're composed of anywhere from a few to hundreds of thousands of alternating layers of two or more substances, each as thin as a few atoms. At the nanoscale—€”one-billionth of a meter—€”the normal boundary and grain structures that constrain a substance's properties can't form, and the laws of classical physics and chemistry give way to the weird uncertainties of quantum mechanics. "One must expect the unexpected" when doing multilayer research, Barbee says.
In creating multilayer materials, scientists can manipulate the thickness of two adjacent layers so they're identical to the interaction lengths characteristic of important physical properties, such as magnetic interaction lengths. The process can yield entirely new properties: extraordinary strength, hardness, heat resistance and optical reflectivity at very short wavelengths.
"Every atomic layer can be part of an interface," Barbee says, "and we can look at interfacial properties that are not accessible by any other means."
Barbee, who played tackle at Stanford on a football scholarship and was named to the Pac-10 All-Conference team in 1957—€”also receiving 2nd team and honorable mention All-American recognition—€”earned his undergraduate degree in metallurgical engineering. His freshman academic advisor had advised him to "to look around and find what you really want to do," he says. "I found metallurgical engineering and materials science, which I really liked."
For his Ph.D. in materials science engineering from Stanford, he did a joint dissertation with the physics department and had labs in both the physics and the materials science buildings. "I was way ahead of the curve for interdisciplinary research," he says. "It was a kind of epiphany. I found that it's a very productive way to work. Now I'm spending my whole time at that interface."
Barbee and his multidisciplinary team of materials scientists, engineers and physicists are asked "to do the things everybody else says are impossible," he says. "And we're the logical ones to do it, because we have such good technicians and engineers working on this. We're the guys that should be doing this work."
At Stanford's Center for Materials Research, Barbee took on the challenge of improving the structural integrity of thick metal films. He hit on the idea of using an emerging technique called magnetron sputtering, in which a material is bombarded with electrically charged particles, knocking loose some of its atoms. The atoms are then deposited on a target surface, where atomic bonding forms a stable coating.
Using an existing vacuum system and $13,000 left over from another project, Barbee and his collaborators successfully layered copper with a variety of other metals, and eventually created a tungsten-carbon multilayer of extremely high structural quality and X-ray reflectivity—€”ideal, as it turned out, for X-ray optics. This magnetron sputter deposition technique was reported to Congress by the National Science Foundation in 1976 as one of four major breakthroughs in materials science that year.
"This materials synthesis technique opened up a whole short-wavelength spectral domain not easily accessible otherwise," Barbee says. "Every time we made an advance and improved the quality (of the multilayer) in terms of X-ray diffraction, we improved the structural quality of the multilayer or nanolaminate material. These materials now are essentially perfect from an X-ray optics perspective."
Barbee came to Livermore in 1985 and set out to advance the sputtering process, develop more advanced multilayer optics, and explore a wider range of multilayer applications. His coatings for telescope mirrors have enabled them to focus light from space in the X-ray and extreme ultraviolet (EUV) wavelengths. The high-resolution optics allows astrophysicists to study previously unseen features of astronomical objects, such as the fluctuating magnetic fields on the sun that help create solar flares and eruptions.
Closer to home, multilayer mirror coatings are the foundation of a major Department of Energy Cooperative Research and Development Agreement (CRADA) involving Livermore, its sister laboratories Sandia and Lawrence Berkeley, and about a half-dozen semiconductor manufacturers. Using a process called extreme ultraviolet lithography, or EUVL, the project is aimed at substantially advancing computer technology by squeezing more transistors and other integrated-circuit features on computer chips. The narrow wavelength of EUV light, about 13 nanometers, allows the EUVL system to print integrated circuit features of 50 nanometers or smaller.
"The first images of the sun with multilayers in 1987 really put EUVL in motion," says Barbee. "We demonstrated we could get these resolutions, so the researchers pushed ahead in the lithography area."
Recognizing the potential of multilayer materials in other applications besides optics, Barbee and Tim Weihs, his postdoctoral researcher, began investigating their use as thermal barrier coatings in the mid-1990s. A three-year CRADA joined Barbee's team with Pratt & Whitney and Rohr Inc. to develop high-performance refractory oxide nanolaminate coatings for aircraft engine blade thermal barriers. The coatings provided thermal isolation that was 2.5 to 3 times greater than then-current technology. The team also worked to develop reactive nanolaminate materials as a means to form high temperature—€“high performance materials and potentially bond materials in new ways.
Weihs left Livermore in 1995 to join the faculty at Johns Hopkins University, where he teamed with another Hopkins professor, Omar Knio, to further develop reactive foils for use as localized heat sources for soldering and brazing. In 2001, Weihs and Knio founded Reactive NanoTechnologies in Hunt Valley, Maryland, to commercialize NanoFoil, an aluminum-nickel multilayer material that can release heat energy in a predictable and controllable manner.
NanoFoil can solder heat sinks to computer chips without damaging them. It can also be used to bond metals, ceramics and polymers, and it can bond dramatically dissimilar kinds of materials without causing them to crack. The technology won an R&D 100 Award from R&D Magazine as one of the top industrial innovations of 2005.
"I credit Troy with launching my career in laminated materials that not only led to a tenured faculty position, but more significantly enabled the birth of a company and the commercialization of LLNL technology in reactive nanolaminates," Weihs says.
"Troy has an amazing ability to both innovate and to execute. He can conceive a new materials technology and then he can perform, either directly or indirectly, all the materials development that is required to bring that technology to life."
Among their 18 patents, Barbee and his colleagues hold two "state of matter" patents for reactive foils—€”having created, in effect, a totally new class of matter—€”with six more patents pending.
Other potential uses of multilayers include high-performance capacitors, ultra high-strength materials, thermoelectric devices, and coatings for gears and bearings, aircraft and automobile engines, and cutting and machine tools. Products incorporating multilayers promise higher strength-to-weight ratios, less friction and wear, higher temperature operation, corrosion resistance, fracture toughness and low electrical resistivity.
Barbee says finding useful applications like these for basic research "is like shooting an arrow into the air and painting a target where it hits. Or as a Nobel-prize-winning chemist once remarked, when asked to define basic or fundamental research, —€˜basic or fundamental research is not-yet-applied research.'
"We really try to do that in this place," he says. "The power of a lab like Livermore lies in the translation of science to technology in as rapid and efficient way as possible. We do very basic stuff, but we do it for a reason, and it gets put to use very quickly. That's what makes the job very exciting for me.
"I'm 68, and now you know why I'm still here; I'm just having a blast. I'm intellectually challenged every day. This work keeps you young."
Charles Osolin is an information officer at Lawrence Livermore National Laboratory.
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