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Luo Group's Research

Research Summary

Research Summary

 Selected Highlights:

National Security Science and Engineering Faculty Fellow (NSSEFF) Award

See: Department of Defense announcement; UC San Diego news  

National Security Science and Engineering Faculty Fellow

AFOSR Flash Sintering

NSF Batteries

NSF Battery Surface

A series of discrete GB interfacial phases (also designated as “complexion”) has been identified in doped alumina [Dillon and Harmer, Acta Mater. 2007] and subsequently other materials. They can be utilized to control sintering, microstructures, and materials properties, offering a revolutionary method for achieving predictive fabrication of materials by design. This figure is adapted from a recent report in Science 33:1730 (2011).

We further purpose to develop grain boundary "phase" (complexion) diagrams as general materials science tool and (perhaps) a useful component for the "Materials Genome" Initiative.  Please find some of our initial efforts below.  Please also see a "cover article" in the August 2012 issue of the Journal of the American Ceramic Society [95: 2358 (2012)] that reviews some of our recent studies and a related news article in Ceramic Tech Today written by Eileen De Guire.

(a) A computed GB λ-diagram for Ni-doped Mo has been validated by a systematic comparison with (b) measured GB diffusivities. This figure is adapted from an “Editors’ Suggestion” in Phys. Rev. B [84: 014105 (2011)]. (According to the PRB: “As a service to both our readers and authors, we list a small number of papers published in Physical Review B that the editors and referees find of particular interest, importance, or clarity.”)

A counterintuitive phenomenon of decreasing GB diffusivity with increasing temperature predicted by (a) a computed λ-diagram was (b) corroborated experimentally. This phenomenon stems from the retrograde solidus line of the Mo-Ni system. Specifically, for a single-phase alloy of Mo + 0.5% Ni, increasing the temperature from 1200 C to 1500 C results in an increasing distance to the solidus line and a greater free-energy penalty for forming liquid-like GBs; thus, the general GBs become “drier” with decreasing diffusivities. Figure adapted from Phys. Rev. Lett. 105: 236102 (2010)

Ni-Bi Complexion Diagram

Triple Line Instability

MURI Extra