Researchers at ETH Zurich have created a new type of foam made of real gold. It is the lightest form ever produced of the precious metal: a thousand times lighter than its conventional form and yet it is nearly impossible to tell the difference with the naked eye. There are many possible applications for the new gold aerogel.
A nugget of real 20 carats gold, so light that it does not sink in a cappuccino, floating instead on the milk foam – what sounds unbelievable has actually been accomplished by researchers from ETH Zurich. Scientists led by Raffaele Mezzenga, Professor of Food and Soft Materials, have produced a new kind of foam out of gold, a three-dimensional mesh of gold that consists mostly of pores.
It is the lightest gold nugget ever created. “The so-called aerogel is a thousand times lighter than conventional gold alloys. It is lighter than water and almost as light as air,” says Mezzenga.
The new gold form can hardly be differentiated from conventional gold with the naked eye – the aerogel even has a metallic shine. But in contrast to its conventional form, it is soft and malleable by hand. It consists of 98 parts air and only two parts of solid material. Of this solid material, more than four-fifths are gold and less than one-fifth is milk protein fibrils. This corresponds to around 20 carat gold.
Drying process a challenge
The scientists created the porous material by first heating milk proteins to produce nanometre-fine protein fibres, so-called amyloid fibrils, which they then placed in a solution of gold salt. The protein fibres interlaced themselves into a basic structure along which the gold simultaneously crystallised into small particles. This resulted in a gel-like gold fibre network.
“One of the big challenges was how to dry this fine network without destroying it,” explains Gustav Nyström, postdoc in Mezzenga’s group and first author of the corresponding study in the journal Advanced Materials. As air drying could damage the fine gold structure, the scientists opted for a gentle and laborious drying process using carbon dioxide. They did so in an interdisciplinary effort assisted by researchers in the group of Marco Mazzotti, Professor of Process Engineering.
The method chosen, in which the gold particles are crystallised directly during manufacture of the aerogel protein structure (and not, for example, added to an existing scaffold) is new. The method’s biggest advantage is that it makes it easy to obtain a homogeneous gold aerogel, perfectly mimicking gold alloys.
The manufacturing technique also offers scientists numerous possibilities to deliberately influence the properties of gold in a simple manner. ” The optical properties of gold depend strongly on the size and shape of the gold particles,” says Nyström. “Therefore we can even change the colour of the material. When we change the reaction conditions in order that the gold doesn’t crystallise into microparticles but rather smaller nanoparticles, it results in a dark-red gold.” By this means, the scientists can influence not only the colour, but also other optical properties such as absorption and reflection.
The new material could be used in many of the applications where gold is currently being used, says Mezzenga. The substance’s properties, including its lighter weight, smaller material requirement and porous structure, have their advantages. Applications in watches and jewellery are only one possibility. Another application demonstrated by the scientists is chemical catalysis: since the highly porous material has a huge surface, chemical reactions that depend on the presence of gold can be run in a very efficient manner. The material could also be used in applications where light is absorbed or reflected. Finally, the scientists have also shown how it becomes possible to manufacture pressure sensors with it. “At normal atmospheric pressure the individual gold particles in the material do not touch, and the gold aerogel does not conduct electricity,” explains Mezzenga. “But when the pressure is increased, the material gets compressed and the particles begin to touch, making the material conductive.”
The Latest on: Gold aerogel
via Google News
The Latest on: Gold aerogel
- Asteroid Mining Could Solve Rare Metal Shortageon January 31, 2020 at 7:26 am
Metallic asteroids are primarily iron and nickel, but can contain rare metals like platinum, gold, iridium, palladium, osmium ... NASA’s Stardust spacecraft passed near comet Wild-2 in 2004 and used ...
- Aerogel: remarkable insulating material of the futureon January 24, 2020 at 8:30 am
Aerogels are advanced materials that, due to their ultra-porous structure ... Available in 3, 4, 5, 8, and 12 contacts, the high quality stainless steel locking rings (V4A) and gold contact plating ...
- 'Plastic gold' build to reduce jewellery weight, benefit electronics, radiation shieldingon January 13, 2020 at 10:05 pm
To achieve these results, the scientists mixed gold nanocrystals, protein fibres, and a polymer latex with water and salt to create a gel, before replacing the water with alcohol. When put into a high ...
- Manufacturing Bits: Jan. 13on January 13, 2020 at 12:09 am
Then, they embedded gold nanocrystal discs. The resulting material also consists of tiny air pockets. In the process flow, the materials are subjected to water. Then, salt is added to create an ...
- Light 18-carat gold created from plasticon January 12, 2020 at 10:00 pm
In addition, the lightweight gold contains countless tiny air pockets ... everything turns it into a homogeneous gossamer-like aerogel. Heat can be further applied afterwards to anneal the plastic ...
- Scientists create 18-carat gold nugget made of plasticon January 12, 2020 at 6:42 am
While the plastic gold will be in particular demand in the ... everything turned it into a homogeneous gossamer-like aerogel. Heat was further applied afterwards to anneal the plastic polymers ...
- Lightweight gold made of plastic is still as pure as your wedding ringon January 11, 2020 at 4:00 pm
Then the water is replaced with alcohol and the mix is placed in a pressure chamber full of CO2, turning the golden plastic into a light aerogel. After that, the gold can be heated to melt and ...
- An 18-carat gold nugget made of plasticon January 10, 2020 at 7:10 am
Lovers of gold watches and heavy jewellery will be thrilled ... everything turns it into a homogeneous gossamer-like aerogel. Heat can be further applied afterwards to anneal the plastic polymers ...
- Global Aerogel Market Expected to Grow with a CAGR of 9% During the Forecast Period, 2019-2024 - ResearchAndMarkets.comon January 10, 2020 at 6:21 am
For more information about this report visit https://www.researchandmarkets.com/r/16pc4e ...
- Aspen Aerogels: Time To Take Iton January 10, 2020 at 5:19 am
Aspen Aerogels (ASPN) is expected to deliver powerful revenue growth during 2020, and the market estimates it will be growing enviously in the following years. Investing in the company presents a ...
via Bing News