ONR YIP: Developing A First-Principles Model of Hot-Electron-Mediated Diffusion
Abstract
In the project ???Developing A First-Principles Model of Hot-Electron-Mediated Diffusion???, Andr?? Schleife (Univ. of Illinois at Urbana-Champaign) requests $510,000 to establish and validate a first principles computational framework: Ehrenfest molecular dynamics, constrained density functional theory, and nudged-elastic band calculations account for hot-electron effects on ion diffusion. This will facilitate energy-efficient flash sintering of Navy-relevant materials and ion implantation for Qbits.Quantitative understanding of how hot-electron distributions influence ion diffusion is of large fundamental interest and is crucial for the Navy and naval research: Emerging light-weight electronic applications require novel, reliable materials. Many typical navalscenarios rely on high-performance structural materials. In this context, focused-ion beam (FIB) processing is used for high-precision manipulation of electronic functional materials; implantation of ions into silicon is a hot candidate for manufacturing of Qbits. For structural materials, sintering is a popular, albeit energy intensive, way of turning powders into solids without liquefaction. Recently, flash sintering was reported as a promising alternative due to its unusually short time scale and significantly lower temperature, which leads to much better energy efficiency and reduced cost and can preserve nanoscale grains during the sintering process. Quantitative and predictive theoretical understanding of these processes is scarce due to a lack of predictive modeling capabilities.The University of Illinois group will utilize a quantum-mechanical first-principles framework to quantitatively predict hot-electron effects on ion diffusion. The group will apply it to study a possible mechanism for flash sintering, where external electric fields drive the material out of equilibrium. The group will investigate whether these fields are capable of accelerating free electrons initially present in the material, so that they excite more electrons from valence into conduction bands via electron-electron scattering. These are then also accelerated in the field, triggering a cascade of excited electrons and leading to a non-negligible free-electron concentration in the conduction band. The group will also apply the technique to study clustering of defects after radiation cascades in FIB machining and ion implantation with the objective to quantify the lowering of the energy barrier for defect diffusion between lattice sites.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2018
- Source ID
- N000141812605
Entities
People
- André Schleife
Organizations
- Office of Naval Research
- United States Navy
- University of Illinois Urbana–Champaign