b'Development of NewINL scientists elucidate fundamental properties of actinide materials and fuels Experimental Capabilityat a microscale that can simplify material synthesis and advance transport based on Focused Ioncharacterization in future studies.Beam Micromachining andA dvanced next-generation reactors demand a solid fundamental understanding of the physical properties of actinide materials and Investigation of Thermophysicalfuels, including transuranic elements. Despite intensive theoretical and experimental efforts, the effect of 4f- and especially 5f-electrons (electrons Properties of Nuclear Materialsin the 5f orbital characteristic of actinide materials, such as uranium, neptunium, at Micro and Mesoscale plutonium, americium, etc.) transport properties, and their interplay with micro- and meso-scale structures, such as grain boundaries, defects, and/or fission products, are still not well understood. The focused ion beam (FIB) instrument enables detailed microstructural characterization (phase identification, grain size/orientation, chemistry, etc.), extraction of single crystal samples, micromanipulation of specimens and other materials, and deposition of conductive materials. The TOTAL APPROVED AMOUNT:FIB technique has been applied to measure electrical properties, but its use to $741,250 over 3 years directly probe thermal conductivity and other transport properties over a wide temperature and magnetic field ranges is novel with no such capability currently PROJECT NUMBER:existing worldwide. The FIB, in conjunction with the newly developed three omega 18P37-008 technique, will allow direct measurement of thermal transport properties of nuclear PRINCIPAL INVESTIGATOR:materials at the micro- and meso-scale. Researchers used this new experimental Krzysztof Gofryk setup to study the thermophysical behaviors of various metallic and oxide nuclear materials, pure minor actinides, and the impact of microstructural features on these CO-INVESTIGATORS: properties. This new experimental capability will be essential for the future validation Daniel Murray, INL of existing theoretical models and simulations, ranging from the nano- and micro-Luca Capriotti, INL scale ab initio (density functional theory, molecular dynamics) to the meso-scale (Multiphysics Object-Oriented Simulation Environment (MOOSE)/MARMOT code).(top) Electron image of a polycrystalline sample containing SmB6 and SmB4. The cubic SmB6 is of main interest (SmB6 grain is marked by the red rectangle) due to the presence of topological insulating states. (bottom) Images of plasma FIB prepared SmB6 single crystals. The dimension of the small (S), midsize (M), and big (B) samples are 20x0.6x7 mm3, 8x7x5 mm3, and 110x70x22 mm3, respectively. Each sample has four platinum contacts deposited by the plasma FIB method. The outer two contacts are current leads, and the inner two contacts are voltage leads.20'