Researchers produce light malleable gold foam

Researchers at ETH Zurich claim to have created a new type of gold, the lightest ever produced. The new material is in the form of foam, which is a thousand times lighter than solid gold.

However, the researchers said it was next to impossible to tell the difference with the naked eye, as the aerogel also has a metallic sheen.

The foam is soft and malleable by hand and comprises 98 parts air and only two parts of solid material. The solid material is four-fifths gold, and less than one-fifth milk protein fibrils, corresponding to 20 carat gold, the researchers said.

A three-dimensional mesh of gold is made mostly of pores. "It is lighter than water and almost as light as air," Raffaele Mezzenga, professor of food and soft materials, who led the research, said, www.rt.com reported.

The scientists created the porous material by heating milk proteins to produce nanometer-fine protein fibres, so-called amyloid fibrils, which they later placed in a solution of gold salt. The protein fibres interlaced to form the basic structure, along which, the gold simultaneously crystallised into tiny particles. The scientists explained, it resulted in a gel-like gold fibre network.

"One of the big challenges was how to dry this fine network without destroying it," said Gustav Nyström, first author of the corresponding study in the journal Advanced Materials.

The big advantage of this process was that it allowed development of gold aerogels that looked regular gold alloys. The scientists were also able to change the colour of the material by altering the size of the gold particles in the basic structure.

According to the team, the new gold foam could be used in jewellery and in watches. It could also be used as a catalyst in the chemical reactions that were more efficient with the presence of gold. Scientists had also demonstrated that the gold foam could be used to develop special pressure sensors.