For more than three decades, ORNL's Shared Research Equipment (SHaRE) User Facility has provided researchers from universities, industry and other national laboratories with two unique commodities: access to an unmatched array of state-of-the-art electron microscopes and collaboration with a highly skilled staff of scientists. These combined resources enable SHaRE's users to investigate and solve previously intractable problems in the fields of materials science, microscopy, physics and chemistry.

As a result of the facility's singular research capabilities, competition for the opportunity to conduct work at SHaRE is intense. Potential users must submit project proposals for review by the facility's proposal review committee, which consists of the nation's top materials scientists and microscopists. SHaRE's director, Karren More, explains that the facility is not only selective in terms of the research proposals accepted, but also looks for research that will maximize the facility's capabilities. "We ask users to justify why they need these specific instruments to do their research," More says. "They're very specialized instruments, so want to ensure they are reserved for only the best science."

In the case of SHaRE, "the best science" runs the gamut of basic materials science issues, as users investigate the structure, composition and chemistry of a wide range of materials. "We have proposals to do just about everything," More says, "but our focus is on solving materials problems that require high-resolution analytical electron microscopy."

Because SHaRE has a variety of specialized electron microscopes, users can examine features of materials that are measured in millimeters down to millionths of a millimeter. Researchers can also examine the same material with different techniques. More says that scientists can probe a material's topography, morphology, grain boundary structure, atomic structure and composition, depending on the type of study the user is conducting. "All of their activities are ultimately related to the physical and chemical structure of the materials with which they are working," she says. "By studying the properties of the materials, they are conducting very fundamental research to understand the mechanisms of how materials behave."

An interactive research environment

Like most of ORNL's user facilities, SHaRE maintains an in-house research mission, as well a user program. When not supporting users, staff members conduct independent research focused on achieving an advanced understanding of how materials are structured and atomicscale microanalysis techniques. As a result of this arrangement, SHaRE users have the benefit of collaborating with scientists who continuously work at the leading edge of materials science and electron microscopy research.

More notes that while most users have a clear sense of what they wish to accomplish with their research projects, they often require staff support from SHaRE to help them achieve their goals. "This is a complicated field," she adds. "We do not expect users to conduct their research in isolation during their visits to the lab. Rather, we attempt to provide a very interactive research environment by assigning experienced staff members who work directly with users and help them conduct their experiments. When users collaborate and interact with our staff, the result is a higher quality of research."

Collaboration and interaction

Kevin Field, a SHaRE user and a graduate student at the University of Wisconsin, echoes More's assessment of the importance of the facility's uniquely skilled staff. "When we come to SHaRE, we conduct all of our work with a staff scientist, so we have access to expertise that might not be available otherwise. I have been collaborating with Jim Bentley, a SHaRE scientist who has been doing this kind of work for decades. I have gained tremendous knowledge simply by working with someone who has been in the field for so many years."

Field's research at SHaRE involves analyzing irradiated steel alloys to understand how these materials would respond to radiation if they are eventually used in next-generation nuclear reactors. Part of his research involves using several different SHaRE instruments to examine irradiated steel samples, characterizing the extent of the phenomenon known as "radiation-induced segregation." The condition occurs when atoms have been knocked out of place by energetic particles in such a way that the uniform crystal structure of the steel is replaced by an uneven distribution of certain elements. This reaction can cause the steel to weaken and eventually crack. Stressing that reliability is a critical concern for steel used in reactor vessels, Field explains that he and his colleagues are trying to determine whether this phenomenon also occurs in a variety of steel alloys. "If it does," he says, "we want to understand the factors that cause such conditions to occur."

Kelly Perry is a SHaRE staff scientist, but until a few months ago she was a SHaRE user and a graduate student at Rensselaer Polytechnic Institute in Troy, New York, studying the structure of polybenzimidazole (PBI), a polymer with critical applications in the development of membranes for hydrogen fuel cells. These fuel cells could be used for combined heat and power units in homes, as well as in methanol-fueled backpack power sources for soldiers in the field. Understanding more about the structure of PBI is a goal along the way to developing more efficient, longer-lasting fuel cells.

As a graduate student, Perry's research involved working with SHaRE staff to determine if relationships existed between the structure and physical properties of PBI membranes that had not previously been investigated. During the course of the study, Perry and her SHaRE colleagues found that, because PBI is 90 percent liquid, the membranes are difficult to study with electron microscopy. They also discovered that the material is easily dehydrated and damaged by the electron beams of the facility's microscopes. Perry and her SHaRE colleagues addressed the problem using a cryogenic transfer system that enables researchers to freeze PBI samples using liquid nitrogen and keep them frozen throughout their analysis. The process protects the samples from becoming dehydrated or degraded by the microscope's electron beam. However, Perry points out that analyzing a frozen sample presents its own set of challenges, both in terms of sample preparation and in distinguishing between characteristics of the sample and anomalies that might have been induced by the freezing process. "It takes time, patience and practice to understand many of these specialized techniques," Perry says. "SHaRE has some of the country's best microscopes and most advanced equipment for sample preparation, both of which are required to perform high-quality microscopy."

Something new every day

More stresses that the true value of the SHaRE user facility is its ability to add depth and breadth to the research experiences of users like Field and Perry. "Our specialty is the analysis of the composition of materials. There isn't a similar collection of instruments anywhere in the country for doing this kind of research." More adds, "It's not that other facilities don't have any comparable instruments, but our success comes from combining the array of instruments we have for doing the full range of materials characterization with the expertise of our staff members, who are leaders in the field."

One benefit of these resources is the fact what while many researchers come to SHaRE to examine a material with a specific technique in mind, the advice of SHaRE staff members often leads them to use several other techniques that provide additional insight into their project. Perry says the SHaRE program is about developing new techniques and new ways to look at materials and understand them. Field adds, "My time at SHaRE has probably been the best research experience I could have ever had. I learn something new every day."

Source: Oak Ridge National Laboratory Review