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Water-mediated surface diffusion mechanism enabling the Cold Sintering Process (Angew. Chem. proof)

Lead

Proof / editorial-markup PDF for the Angew. Chem. Int. Ed. communication on cold sintering of ZnO with experiments and ReaxFF MD (DOI 10.1002/anie.201904738). Prefer [[2019sengul-venue-water-mediated]] (or [[2019sengul-venue-water-x2010]]) for version-of-record curation.

Summary

Cold sintering processes densify ceramic powders at dramatically lower temperatures than conventional thermal sintering by exploiting transient aqueous films that mediate dissolution–reprecipitation and grain-boundary mobility. This Angewandte Chemie International Edition communication (DOI 10.1002/anie.201904738) combines experiments on zinc oxide with ReaxFF molecular dynamics to argue that reduced activation energies for grain growth under cold sintering arise from acidic, water-mediated surface chemistry rather than from conventional bulk diffusion alone. The mechanistic picture highlights that acidic transients strengthen Zn²⁺ surface adsorption and that hydroxylation can mobilize surface species that accelerate diffusion and recrystallization instead of merely passivating the oxide. Adri C. T. van Duin is a coauthor, linking the work to the group’s reactive modeling of oxide interfaces in electrochemical and processing environments. This wiki slug registers proof PDF bytes; narrative alignment and stable pagination should be checked against [[2019sengul-venue-water-mediated]] or related version-of-record slugs.

Methods

Proof PDF role: N/A to treat this ingest as the sole authoritative protocol; [[2019sengul-venue-water-mediated]] and the VOR / SI have typeset figure-to-Methods mapping.

Experiments / MD (summary). CSP-style experiments on ZnO and ReaxFF molecular dynamics of hydrated and acidified ZnO surfaces rationalize the low activation energy for grain growth via water-mediated surface pathways. 1 — MD: 3D PBC supercells with thousands of atoms (exact supercell in Angew. VOR); NVT or NPT ensemble with timestep on the order of 0.1 fs and equilibration/production ps–ns spans and Nose–Hoover thermostat as in the VOR; LAMMPS is the typical engine for this ReaxFF line ( confirm in SI). Temperature ~300 K and other K targets for surface diffusion analysis are in the main text. Hydrostatic pressure in MD ( bar ) and any Parrinello–Rahman barostat N/A to reproduce on this proof slug—use VOR. 2 — Force-field training: N/A. 3 — Electric field, umbrella, metadynamics: N/A unless the VOR adds them.

Findings

Synthesis (aligned with the communication). The work posits that CSP reduces the apparent activation energy for grain growth in ZnO by surface-mediated pathways where H⁺-rich, water-containing transients make Zn²⁺ adsorption and transport kinetically accessible, relative to conventional sintering—and that hydroxylation is not merely a passivating, lubricant-only effect in the ReaxFF-supported picture.

Comparisons / levers follow figures on the VOR; this proof page is not where extraction should end for d vs T kinetics or prefactors.

Limitations (corpus). Proof duplicates may have reordered figures; use [[2019sengul-venue-water-mediated]]. Reaxff caveats in the Limitations section below still apply.

Limitations

Proof PDFs may retain editorial markup, altered line breaks, and non-final author affiliations; readers preparing citations should download the issue PDF from the publisher. ReaxFF models of acidified oxide interfaces inherit force-field approximations for proton transfer and charged defects that require contextual validation.

Relevance to group

The publication is a flagship example of ReaxFF applied to oxide processing with experimental co-validation, useful for theme hubs linking ceramics, aqueous interfaces, and reactive force fields.

Citations and evidence anchors

Reader notes (navigation)