Goldest Gold Of All

[Hervé]

New microcrystalline form of gold is much golder than normal gold

Michael Marshall New Scientist
Sat, 14 Jul 2018 16:44 UTC

Not gold enough? © Susan E. Degginger / Alamy Stock Photo

New form of gold is much golder than normal gold

All that glitters is not gold - but sometimes it really, really is. Researchers have made a new kind of gold crystal that is even more gold-like than regular gold.

Gold is a precious metal, which means that as well as being attractively shiny it is almost entirely chemically inert. Unlike other metals, it does not rust when exposed to air, and retains its lustre indefinitely.

It's said this property is why wedding rings are traditionally made of gold: it represents an eternity of love. Silver is another such "noble metal", but even silver reacts slowly with oxygen in the air, so requires occasional polishing.

In 2015 Giridhar Kulkarni of the Centre for Nano and Soft Matter Sciences in Bangalore, India and his colleagues described a new form of gold: microcrystals measuring between 2 and 17 micrometres. They made them by heating gold chloride to 220 °C for 30 minutes in the presence of a second chemical called tetraoctylammonium bromide. They look like angular, knobbly sausages.

Microcrystal test
Now, Kulkarni has now found that the microcrystals are even less reactive than ordinary gold, by exposing them to two substances that normally dissolve the shiny stuff.

The first was mercury, a metal that is liquid at room temperature. The team dunked the microcrystals into pots of mercury and did the same to similar-sized chunks of ordinary gold. While the normal gold disappeared within 6 minutes, the microcrystals were unchanged after 27 hours.

Next, they used aqua regia, a mixture of nitric acid and hydrochloric acid once used by alchemists to test for fake gold - hence the phrase "acid test". Ordinary gold dissolved within 70 minutes, but the microcrystals survived - although they did succumb when the aqua regia was made more concentrated.

The team calls the microcrystals "nobler than the noblest". "It appears that these are the least reactive substances produced," says Kulkarni.

The microcrystals are so unreactive because of the way gold atoms in them are arranged. The atoms in ordinary gold are arranged in a cubic pattern, but in the microcrystals the cubes have been stretched or distorted. This means they have unusually-shaped surfaces, which the other chemicals can't latch onto.

This new gold might ultimately be useful for making other novel substances. In a bizarre twist, in 2017 the team showed that "they exhibit catalytic activity, which is unknown for ordinary bulk gold," says Kulkarni. That means despite not reacting themselves, they can drive other chemical reactions, which could help make new discoveries.

Journal reference: Angewandte Chemie , DOI: 10.1002/anie.201804541

[Jad]

I hope that Joe from the Carolinas wont remind you of how much of real humdinger this thread is! 😂

[The Moss Trooper]

Is there a new Sheriff in town?

[Joe from the Carolinas]

Posted by Jad (here)
I hope that Joe from the Carolinas wont remind you of how much of real humdinger this thread is! 😂

Posted by The Crimson Horse Blanket (here)
Is there a new Sheriff in town?

Howdy ya'll. To be fair, this thread really IS a real good humdinger!!

[Bill Ryan]

Posted by The Crimson Horse Blanket (here)
Is there a new Sheriff in town?

Making all the mods laugh here, behind the scenes.

We're sorting all this out. No bad guys in sight!

[Valerie Villars]

At least Joe isn't claiming to be the reincarnation of Will Rogers. Sorry, I couldn't resist.

[Joe from the Carolinas]

Posted by Valerie Villars (here)
At least Joe isn't claiming to be the reincarnation of Will Rogers. Sorry, I couldn't resist.

[Bill Ryan]

Posted by Joe from the Carolinas (here)

Posted by Valerie Villars (here)
At least Joe isn't claiming to be the reincarnation of Will Rogers. Sorry, I couldn't resist.

He still has his badge, but we've confiscated his sixgun just for a few hours.

[Hervé]

...


... one would have thought that the gold-rush era was gone... but the fever is still there


Anyway...

[Jad]

Posted by Hervé (here)
...


... one would have thought that the gold-rush era was gone... but the fever is still there


Anyway...

You’re right now that France 🇫🇷 has brought back the Gold home ✌️😉

[Foxie Loxie]

Speaking of gold....I often think of Bob Dean's comment that we have been giving gold to a race that has been helping us. They eat it in its white powder form, apparently!

Well, Moses DID feed his people gold in the desert & they wandered around for 40 years on the strength of that & the Manna...right?!

[Hervé]

Scientists accidentally stumble onto technique for melting gold at room temperature

Colm Gorey Silicon Republic
Tue, 20 Nov 2018 22:05 UTC

© rcfotostock/Stock.adobe.com

Scientists were dumbfounded after finding it is possible to melt gold at room temperature using an electron microscope.

For thousands of years, famous scientists and alchemists attempted to find a way to turn common metals into gold. While this proved to be a thankless pursuit, a new discovery announced by a team from Chalmers University in Sweden has managed to find an altogether different and mysterious property of gold itself.

After placing a small piece of gold in an electron microscope, researcher Ludvig de Knoop ramped up the magnification to the maximum and increased the electric field step by step to see what would happen to the gold's atoms. To his amazement, he noticed that the surface layers of gold had actually 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," De Knoop said.

Publishing his findings in Physical Review Materials along with his university colleagues and Finnish theoretician Mikael Juhani Kuisma, De Knoop explained that the melting occurred because the atoms became excited. Under the influence of the electric field, they suddenly lost their ordered structure and released almost all their connections to each other.

When they examined it further, they discovered it was also possible to switch between a solid and molten structure. The researchers have stressed this discovery to not just be spectacular, but also groundbreaking scientifically.

Using theoretical calculations, the researchers believe it is possible to melt gold at room temperature because the surface melting can be seen as a so-called low-dimensional phase transition.

Eva Olsson, professor of the Department of Physics at Chalmers University, said:

"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."

========================================

Ah, the mysteries of the Electric Universe...


This also adds to an indication as to why gold is mostly associated with two major piezoelectric minerals: Quartz and arsenopyrite...