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Luo Group's Research
A series of discrete grain boundary (GB) 2-D 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 prior report in Science 333: 1730 (2011).
There are more details (e.g., in the bilayers in Ni-Bi)...
Development of Interfacial "Phase" (Complexion) Diagrams
A Few Examples:
(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)
Batteries, Solid Electrolytes and Supercapacitors
Viewpoint: Scripta Materialia, 146: 260 (2018)
Water-Assisted Flash Sintering (WAFS)
Two-Step Flash Sintering (TSFS)
Selected Other Research