Apr 10, 2025
11:15am - 11:30am
Summit, Level 4, Room 421
Shibo Tan1,Gabrielle Kamm2,Alex Stangel1,Paul Chao1,Ashwin Shahani1,Robert Hovden1,Karena Chapman2,Wenhao Sun1
University of Michigan1,Stony Brook University, The State University of New York2
Shibo Tan1,Gabrielle Kamm2,Alex Stangel1,Paul Chao1,Ashwin Shahani1,Robert Hovden1,Karena Chapman2,Wenhao Sun1
University of Michigan1,Stony Brook University, The State University of New York2
Solid-state synthesis is the primary method for manufacturing inorganic materials, yet lacks mechanistic theories to predict optimal reaction temperatures. Recent observations suggest transient liquid intermediates may serve as diffusion media in solid-state reactions at subsolidus temperatures. Here, we hypothesize that in a solid-state reaction
A+
B →
AB, precursors
A and
B first melt into a metastable liquid phase before forming the solid AB product. This theory derives the reaction onset temperature by extending liquidus curves into the metastable eutectic region of the temperature-composition phase diagram. We validate this theory using a thermal gradient heater coupled with
in situ synchrotron X-ray diffraction to produce temperature-time-transformation curves, which largely align with theoretical predictions.
In situ transmission electron microscopy at the reaction onset temperature reveals melting between nanoscale precursor particles.
Calculations based on
in situ nanotomography characterization of reaction precursors and products demonstrate that the observed reaction rates require diffusivity values significantly higher than those achievable through solid-state vacancy-mediated diffusion, strongly supporting the presence of a liquid diffusion medium.