Campus Units

Materials Science and Engineering, Electrical and Computer Engineering, Microelectronics Research Center (MRC)

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

12-30-2020

Journal or Book Title

Angewandte Chemie International Edition

DOI

10.1002/anie.202013489

Abstract

Advances in hybrid, high‐density and flexible/wearable electronics demand low temperature metal processing. Undercooled metals have emerged as a solution to low temperature soldering and printing of conductive traces. The process of undercooling, however, relies on frustration of liquid‐solid transition mainly through increase in activation energy by: i) elimination heterogeneous nucleants, or ii) frustrating homogeneous nucleation. We inferred that passivating oxide layers present an active platform that can isolate the core from heterogenous nucleants (physical barrier) while also raising the activation energy (thermodynamic/kinetic barrier) needed for solidification. The latter is due to composition gradients (speciation) that establishes a sharp chemical potential gradient across the thin (0.7‐5 nm) oxide shell hence slows homogeneous nucleation. When this speciation is properly tuned, the oxide layer presents a previously unaccounted for interfacial tension in the overall energy landscape of the relaxing material. Herein, the role of surface oxide structure in enhancing and maintaining undercooling is demonstrated. We demonstrate that; i) the integrity of the passivation oxide is critical in stabilizing undercooled particle, a key tenet in developing heat‐free solders, ii) that inductive effects play a critical role in undercooling, and iii) that magnitude of the effect of the passivating oxide can be larger that of size in undercooling.

Comments

This is the peer-reviewed version of the following article: Martin, Andrew, Boyce S. Chang, Alana M. Pauls, Chuanshen Du, and Martin M. Thuo. "Stabilization of Undercooled State via Passivating Layers." Angewandte Chemie International Edition (2020), which has been published in final form at DOI: 10.1002/anie.202013489. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Posted with permission.

Copyright Owner

Wiley‐VCH GmbH

Language

en

File Format

application/pdf

Available for download on Thursday, December 30, 2021

Published Version

Share

COinS