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EFRC - Center for Defect Physics in Structural Materials

FWP/Project Description: 

This project will help incorporate our new, efficient, order-N (where N is the number of scattering sites in a defected crystal) method for solving the Poisson’s equation for site-centered electronic-structure method used within the center (i.e., the LSMS code) for critical simulations. The method will be extended in collaboration to develop capabilities for relaxation by atomic forces within this new formulation for full quantum simulation of large-scale defected systems.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences. The Energy Frontier Research Center is funded through the US DOE Oak Ridge National Laboratory.

Solid State Processing of Fully Dense Anistropic Nanocomposition Magnets

FWP/Project Description: 

The project proposes a new solid state processing technology which will transform how current magnets are fabricated, resulting in a dramatic cost decrease and significant reduction of the rare earth (RE) content while actually enhancing the magnetic performance of the magnets. This will be accomplished by a revolutionary solid-state processing technique called Friction Consolidation and Extrusion (FC&E). Processing of sintered (Nd, Dy)-Fe-B type magnets in use today require 2-4 wt.% excess RE elements relative to the stoichiometric compound, with up to 4-10 wt. % of the alloy being Dy. The new class of exchange coupled hard / soft nanocomposite magnets have been theoretically predicted to be twice as strong as the current state of the art rare earth magnets, while the total RE content can be reduced by 30% or more. The challenge remains to develop a reliable and economical process to produce a 100% dense alloy with nanoscale grains, full magnetic alignment and a uniformly distributed nanoscale soft magnetic phase. The role of The Ames Laboratory will be to 1) determine optimal length scales of the nano-structuring using advance computational tools, 2) provide feedstock for the FC&E process, 3) characterize high performance magnet alloys produced by the PNNL for their microstructure and phase distributions using scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) and Transmission electron microscopy (TEM).

This research is supported by the U.S. Department of Energy, Advanced Research Projects Agency-Energy.

Electronic Structure of Warm Dense Matter via Multicenter Green's Function Technique

FWP/Project Description: 

The proposed research addresses the Warm Dense Matter area identified in the Report of the ReNeW in HEDLP. The electronic structure, equation of state, radiative, and transport properties of warm electrons in an amorphous or disordered configuration of ions are not well described by either solid state or plasma models. Such warm-dense systems share the characteristic of the solid state that multi-center scattering effects are of paramount importance in forming bands of valence states, but furthermore require the description of an appreciable occupation in higher energy and angular momentum channel continuum states.

This research is supported by the U.S. Department of Energy, Office of Fusion Energy Sciences.

“Explosive” atom movement is new window into growing metal nanostructures

“The textbook said we should see slow, gradual and random. But what we saw? BOOM! Fast, explosive and organized!” said Michael Tringides, physicist at the U.S. Department of Energy’s Ames Laboratory and a professor of physics and astronomy at Iowa State University.

Tringides is talking about the unusual atom movement he saw when they dropped a few thousand lead atoms onto a flat, smooth lead-on-silicon surface, all at low temperatures, and looked at an area just one-twentieth the width of a human hair.


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