ORNL's Center for Nanophase Material Sciences delivers a one-two punch—providing both a cutting-edge research facility open to scientists around the globe and a world-class nanoscience program. "These two activities enhance each other," says CNMS director Sean Smith. "That's the effect we've been working toward during our first five years. Now that we've built up our user base, we receive consistently high-quality user proposals. As a result, both our users and the laboratory benefit from being involved in these projects; it really is a synergistic relationship."
Microscopy images of bismuth ferrite nanocapacitors, lithium nanoparticles, and self-assembled molecular hexamers. Images: Imaging Functionality Group at ORNL's Center for Nanophase Materials Sciences
One of five Department of Energy nanoscience centers, CNMS attracts users from both inside and outside ORNL for the same reasons: the center has specialized equipment researchers need and nanotech experts to boost the quality of users' research projects. Another huge bonus for CNMS users is the center's proximity to other materials research facilities. Just next door is the Spallation Neutron Source, the world's most powerful pulsed-neutron research facility; and the nation's most powerful research reactor, the High Flux Isotope Reactor, is just down the road. This unprecedented concentration of analytical capabilities, combined with ORNL's diverse R&D portfolio, is particularly attractive to users who want to analyze the material they work with in a number of different ways—without traveling all over the country.
A powerful tool
Research and development at the nanoscale is conducted across a range of disciplines at ORNL—from traditional nanotech fields like materials science to relative newcomers like nanobiology. Smith explains that the synergy created by scientists from different domains exchanging ideas is an extremely powerful tool for promoting scientific innovation. "That's why the CNMS is not tied to one specific project or scientific investigation area. We have a larger and more broadly user-encompassing mandate that allows us to encourage a host of different areas of investigation."
In recent years the work of the center's Imaging Functionality group has been particularly successful in developing new scanning probe microscopy methodologies. The group has developed a suite of techniques for deciphering the structure and dynamic interactions of semiconductor metal-oxide films. These materials are a key component of energy storage devices, such as batteries, so understanding them in more detail paves the way for batteries that are more efficient, long-lasting and affordable.
"If you look at the matrix of the lab's capabilities," Smith says, "the ability to characterize energy-related materials—to understand their structure at the nanoscale—will become increasingly important." At present, these capabilities are being put to use not only in research aimed at building better batteries, but also in solar energy research. Solar cells—Researchers from both the CNMS and the SNS are focused on understanding and creating a new generation of devices that can convert light into electricity, such as the photovoltaic cells used in solar collectors. They are particularly interested in determining how the nanostructure of the materials used in solar cells is related to how the cells perform.
To tease apart the intricacies of this relationship, researchers conduct detailed studies of photoelectric films using microscopic, x-ray and chemical techniques at the CNMS. Then they take their materials to the SNS to perform additional tests using neutron analysis. Smith explains that the center's three areas of specialty—synthesizing new materials, making hybrid materials from polymers and inorganic substances, and analyzing materials—provide CNMS with a multipronged way of determining the structure of a material and exploring the relationship between its structure and its performance.
Smith expects that the next generation of the center's work in the area of solar cells will capitalize on the ability to relate structure to performance. CNMS researchers will characterize the photoelectric film production process in real time, using neutron-scattering instruments at the SNS. "We'll examine the behavior of the materials throughout the process," Smith explains, "beginning with the threedimensional fluid, depositing the fluid on the substrate, evaporating it, and creating the final thin-film device. We want to look at the dynamics of the process at each stage and understand their implications for the finished device."
In addition to lending its expertise to research efforts in established nanotech fields like materials science, CNMS hosts users who are investigating various aspects of nanobiology. These include research into how nanoparticles accumulate in living systems and investigations of the use of nanoparticles as delivery vehicles for genes and drugs for various kinds of therapy.
One particularly unusual nanobiology project employs microbes to produce nanoparticles for industry. This cross-disciplinary effort began several years ago when researchers in ORNL's Biosciences Division discovered that certain microbes, harvested from deep drilling operations, naturally produced nanoparticles in the form of metallic iron clusters on their cell membranes. "This observation was particularly interesting," Smith says, "because nanoparticles are widely used in industry, but their synthesis is generally costly and less easily scaled to large quantities than would, in principle, be possible using the microbe route." Scientists at ORNL are studying the potential for using similar microbes as a source of low-cost nanoparticles for applications such as creating photovoltaic thin films. In addition, the CNMS is using its analytical resources to get a better understanding of the nature of nanoparticles produced by biological processes and how they might be used in alternative energy applications and in materials that imitate biological materials. "Without facilities like CNMS," Smith observes, "we would have no way to learn what's going on in these biological systems at this level of detail."
The value of CNMS is rooted not only in its unique research facilities but also in its expertise in producing and characterizing materials at the nanoscale. Smith notes that the center brings a unique perspective to addressing research problems. "For example," he says, "in the microbe study I mentioned earlier, the researchers knew that the microbes were making nanoparticles on their membranes, but problems arose when they tried to harvest the particles, which were sticking together and forming clumps. At the suggestion of one of our staff members, the researchers introduced small quantities of dispersant into the process. That didn't seem to bother the microbes, but it prevented the clumping and allowed the scientists to control the size and distribution of the particles."
This illustrates the ability of CNMS to find effective, if unexpected, solutions. "Nanoscience is an incredibly broad area which impacts technology in health, medicine and many other fields," Smith says. "We don't do research in all of these areas, but we can facilitate interactions among researchers and help move the research forward."
Despite the broad applicability of the center's findings and facilities, Smith expects two areas of nanoscience to dominate its activities over the next few years. "First," he predicts," "research into energy materials is going to be huge. We are already heavily engaged in designing new materials to support and advance energy technologies, such as batteries, supercapacitors and solar panels, and we will continue to be."
Smith also expects nanomedicine and nanobiology to become increasingly important. He notes that these are areas in which CNMS works even more frequently than usual with partners across ORNL. "Our mission is basic energy sciences," he explains, "but by collaborating with research groups who are engaged with things like gene therapy and emulating biological systems, we can help them make progress in those areas as well. Nanoscience plays an enormous role in these fields, and we will be pushing hard to help them reach their goals.
"This kind of cross-disciplinary research is what I'm talking about when I say that CNMS can be a tremendous facilitator," Smith says. "Helping people in diverse areas to better understand their materials or processes, or to understand how to work more effectively at the nanoscale, allows them to move their research forward in their own domains, and that benefits all of us."— Jim Pearce