Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists solve the golden puzzle of calaverite

24.09.2018

Scientists from Russia and Germany shed light on the crystalline structure of calaverite, foretelling the existence of a new gold compound previously unknown to chemists. The results of their study were published in the reputable scientific journal PNAS.

A gold tellurite with the chemical formula AuTe2, calaverite may not only be a source of gold, but displays highly incommensurate modulation in the positions of gold and tellurium atoms in its crystals.


Formation of the Te-Te dimers due to charge disproportionation on Au sites.

Credit: S. V. Streltsov et al./PNAS

This means that calaverite's crystal lattice cannot be explained by Haüy's law which describes the crystals of most minerals. Calaverite and other incommensurate crystals have long been a mystery for crystallographers.

In the 1970s, scientists found a way of describing their structures using 4D space instead of the customary 3D space in their calculations. However, researchers have been clueless as to the reasons of such weird behavior of calaverite crystals.

Research teams from the RAS Institute of Metal Physics (led by Professor Sergey Streltsov), the University of Cologne (led by Professor Daniil Khomsky), Skoltech and the Moscow Institute of Physics Technology (MIPT) (led by professor Artem Oganov) cracked the mystery of incommensurate calaverite crystals, gaining insights into their electronic spectra obtained in the experiments and their superconducting capability created by pressure or additives.

"The simple reasoning suggests that gold should be divalent in this compound in much the same way as iron is in FeS2, known as "fool's gold". Any chemist understands that divalent gold is extremely unstable and tends to become monovalent and trivalent, but there lies the rub: first, 3+ is too high a valence and, second, there is no way you can place monovalent or trivalent gold (assuming it exists in the first place) on calaverite's triangular lattice with the pattern repeating in each direction.

Therefore, it's the nature that dictates the compromise by smoothly changing the valence of gold in the crystal. Tellurium's environment responds to the change and this results in bizarre crystal lattices," explains Sergey Streltsov

The scientists also relied on the USPEX ? an advanced evolutionary algorithm created by Artem Oganov and intensively used by crystallographers worldwide ? to predict all the known stable tellurides of gold and a new telluride, AuTe, unknown until now.

"There's quite a story behind calaverite. Apart from its marked impact on the Gold Rush, the mineral has been a headache and a great paradox for crystallographers for decades. The deeper you dug into it, the more new questions came up.

Our team has succeeded in interlacing all the oddities of calaverite within a simple model, so experimenters can now hunt for the new compound we predicted, AuTe, which I'm sure is full of new riddles," says Professor of Skoltech and MIPT Artem Oganov.

Media Contact

Ilyana Zolotareva
zolotareva.id@mipt.ru
7-977-771-4699

 @phystech_en

https://mipt.ru/english/

Ilyana Zolotareva | EurekAlert!
Further information:
https://mipt.ru/english/news/scientists_solve_the_golden_puzzle_of_calaverite?bitrix_include_areas=Y&CODE=scientists_solve_the_golden_puzzle_of_calaverite&clear_cache=Y
http://dx.doi.org/10.1073/pnas.1802836115

Further reports about: bizarre crystal lattice crystallographers crystals

More articles from Physics and Astronomy:

nachricht Scientists see energy gap modulations in a cuprate superconductor
02.04.2020 | DOE/Brookhaven National Laboratory

nachricht BESSY II: Ultra-fast switching of helicity of circularly polarized light pulses
02.04.2020 | Helmholtz-Zentrum Berlin für Materialien und Energie

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A sensational discovery: Traces of rainforests in West Antarctica

90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous

An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...

Im Focus: Blocking the Iron Transport Could Stop Tuberculosis

The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.

One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...

Im Focus: Physicist from Hannover Develops New Photon Source for Tap-proof Communication

An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.

A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...

Im Focus: Junior scientists at the University of Rostock invent a funnel for light

Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.

The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.

Im Focus: Stem Cells and Nerves Interact in Tissue Regeneration and Cancer Progression

Researchers at the University of Zurich show that different stem cell populations are innervated in distinct ways. Innervation may therefore be crucial for proper tissue regeneration. They also demonstrate that cancer stem cells likewise establish contacts with nerves. Targeting tumour innervation could thus lead to new cancer therapies.

Stem cells can generate a variety of specific tissues and are increasingly used for clinical applications such as the replacement of bone or cartilage....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

13th AKL – International Laser Technology Congress: May 4–6, 2022 in Aachen – Laser Technology Live already this year!

02.04.2020 | Event News

“4th Hybrid Materials and Structures 2020” takes place over the internet

26.03.2020 | Event News

Most significant international Learning Analytics conference will take place – fully online

23.03.2020 | Event News

 
Latest News

Scientists see energy gap modulations in a cuprate superconductor

02.04.2020 | Physics and Astronomy

AI finds 2D materials in the blink of an eye

02.04.2020 | Information Technology

New 3D cultured cells mimic the progress of NASH

02.04.2020 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>