Gas-assisted transformation of gold from fcc to the metastable 4H phase
The metastable hexagonal 4H-phase gold has recently attracted extensive interest due to its exceptional performance in catalysis. However, gold usually crystallizes to its lowest free energy structure called face-centered cubic (fcc) . The phase transformation from the stable fcc phase to the metast...
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Published in | Nature communications Vol. 11; no. 1; p. 552 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
28.01.2020
Nature Publishing Group Nature Portfolio |
Subjects | |
Online Access | Get full text |
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Summary: | The metastable hexagonal 4H-phase gold has recently attracted extensive interest due to its exceptional performance in catalysis. However, gold usually crystallizes to its lowest free energy structure called face-centered cubic
(fcc)
. The phase transformation from the stable
fcc
phase to the metastable 4H phase is thus of great significance in crystal phase engineering. Herein, we report this unusual phenomenon on a 4H gold nanorod template with the aid of CO gas and an electron beam. In situ transmission electron microscopy was used to directly visualize the interface propagation kinetics between the 4H-Au-nanorod and
fcc
-Au nanoparticle. Epitaxial growth was initiated at the contact interface, and then propagated to convert all parts of these
fcc
nanoparticles to 4H phase. Density functional theory calculations and ab initio molecular dynamics simulations show that the CO molecules can assist the Au diffusion process and promote the flexibility of Au particles during the epitaxial growth. The phase transformation was driven by the reduction of Gibbs free energy by eliminating the interface between
fcc
and 4H phases.
Crystal phase engineering enables the growth of nanostructures with controlled crystal phases that show superior functional properties. Here, the authors find that CO gas-metal atom interactions combined with the electron beam can trigger phase transformations of precious metals at room temperature. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 2041-1723 2041-1723 |
DOI: | 10.1038/s41467-019-14212-z |