Terrence J. Udovic
(301) 975-6241
As a partner in the Metal Hydride Center of Excellence, the National Institute of Standards and Technology (NIST) provides critical neutron metrologies and Calphad-based computational thermodynamics expertise to aid in more intelligent materials design.
The study of hydrogen in materials by neutron scattering, imaging, and trace-analysis techniques is a critical component of the center. This is largely due to the novel properties of the neutron and its interactions with matter, especially the different isotopes of hydrogen. The unusually large neutron-scattering cross section for hydrogen can be routinely exploited by a range of experimental neutron methods to probe the amount, location, bonding states, and diffusion of hydrogen in any promising hydrogen-storage material.
The thermal and cold-neutron beams at NIST, combined with state-of-the-art instrumentation developed over the past decade, provide the nation with its only comprehensive array of world-class neutron probes with respect to sensitivity and dynamic range. NIST has substantial expertise in the use of neutron methods for studying hydrogen in metals going back four decades.
In addition, NIST has a 20-year history in thermodynamic modeling using the Calphad (Computer Coupling of Phase Diagrams and Thermochemistry) method, including its ability to treat materials with three or more components. This method provides a way to incorporate the molecular-dynamics or first-principles calculations of promising materials into an overall temperature-pressure-composition framework to search for better materials with, for example, the lowest enthalpy of formation. The method includes an assessment of hydrogen content, heats of reaction, and phase-reaction sequences during hydriding.