Researchers Manage to Melt Gold Surface at Room Temperature Using an Electron Microscope

An increase in tension could lead to unexpected things—and it is no different for gold atoms. At present, for the first time, scientists from, among others, Chalmers University of Technology have managed to melt the surface of a gold object at room temperature.

The illustration shows the atoms of a gold cone exposed to a strong electric field. We also see the field (around the tip of the cone) that excites the gold atoms. They break almost all their connections to each other and the surface layers begin to melt. (Image credit: Alexander Ericson)

A small piece of gold was placed in an electron microscope by Ludvig de Knoop, from Chalmers’ Department of Physics. He observed it at the highest level of magnification by a stepwise increase in the electric field to extremely high levels, and was fascinated to view the way it has an impact on the gold atoms.

When he analyzed the atoms in the recordings from the microscope, he observed something mind-blowing. Actually, the surface layers of gold had melted—at room temperature.

I was really stunned by the discovery. This is an extraordinary phenomenon, and it gives us new, foundational knowledge of gold.

Ludvig de Knoop, Department of Physics, Chalmers University of Technology

The gold atoms actually became excited. All of a sudden, they lost their ordered structure under the impact of the electric field and released nearly all their connections to one another.

Through further analyses, the team found that it was also feasible to switch between a solid and a molten structure.

The discovery of the way gold atoms can lose their structure in this manner is not only splendid but also path-breaking scientifically. Ludvig de Knoop and his team collaborated with the theoretician Mikael Juhani Kuisma, from the University of Jyväskylä in Finland, to open up new avenues in materials science. The outcomes of the study have been reported in the Physical Review Materials journal.

Using theoretical calculations, the researchers were able to describe the reason for gold to melt at room temperature. Probably, the surface melting can be considered to be a purported low-dimensional phase transition. In that event, the discovery is related to the research field of topology, where pioneers David Thouless, Duncan Haldane, and Michael Kosterlitz received the Nobel Prize in Physics, 2016. With Mikael Juhani Kuisma leading the study, the team is now looking forward to that possibility. Regardless of the case, the potential to melt gold surface layers in this way opens the door for several innovative practical applications in the future.

Because we can control and change the properties of the surface atom layers, it opens doors for different kinds of applications. For example, the technology could be used in different types of sensors, catalysts and transistors. There could also be opportunities for new concepts for contactless components.

Eva Olsson, Professor, Department of Physics, Chalmers University of Technology

However, for the time being, those who intend to melt gold without an electron microscope might have to visit the goldsmith.

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