Stable armchairlike hexazine N6 ring in tungsten hexanitride
2021-02-10
(Press-News.org) Tungsten hexanitride with armchairlike hexazine N6 ring has been synthesized by a group of scientists led by Dr. Jin Liu and his former postdoc Nilesh Salke at HPSTAR (Center for High Pressure Science & Technology Advanced Research). WN6 is a promising high-energy-density and superhard material. Their findings are published in the recent issue of Physical Review Letters.
Diatomic nitrogen is the most abundant molecule in Earth's atmosphere accounting for almost 78% volume. The strong triple bond in nitrogen makes it very stable and unreactive at near ambient conditions. However, in the intense-pressure and high-temperature conditions, nitrogen will behave entirely differently, it can form double- or even single-bonded structure or react with other elements to form novel nitrides. Single-bonded polymeric nitrogen or nitrides possessing single-bonded nitrogen are of great scientific interest as a high-energy-density material. And transition metal nitrides are the very promising candidates that might contain the planar nitrogen hexazine (N6) ring which are predicted to be impossible to stabilize experimentally due to the lone pair repulsion.
The team created WN6 in a laser-heated diamond anvil cell by elemental reaction between tungsten and nitrogen above pressure of about 1.3 Mbar and temperature of ~3500 K. In-situ synchrotron x-ray diffraction (XRD) allowed them to identify the tungsten hexanitride phase, crystallizing with novel armchair-like N6 rings, and the high-pressure Raman spectroscopy measurement confirmed the presence of N-N single bonds in N6 rings. Further theoretical calculations also support their experimental observations.
"The armchair-like hexazine nitrogen sublattice in the WN6 is remarkable and comparable to that in the polymeric nitrogen phases, making it a promising high-energy-density material candidate," remarked Dr. Nilesh Salke, now a postdoctoral researcher at the University of Illinois at Chicago.
Additionally, WN6 shows a Vickers hardness of up to?57 GPa, the highest hardness among all transition metal nitrides along with good toughness. They credited the ultra-stiffness of WN6 to balance between the attractive interaction of N6 rings with W atoms and the repulsive interaction of N6 rings with each other based on theoretical calculations.
"To our knowledge, this is the first experimental report on the single-bonded transition metal nitride," said Dr. Jin Liu, "We believe that this work will stimulate further experimental efforts to synthesize other nitrides with novel structural, chemical, and physical properties."
"Our experimental demonstration of stabilizing armchairlike hexazine N6 ring in WN6 paves the way for future efforts to stabilize planar hexazine ring," added Dr. Liu.
INFORMATION:
More information: Tungsten Hexanitride with Single-Bonded Armchairlike Hexazine Structure at High Pressure, Salke et al., Phys. Rev. Lett. DOI: https://doi.org/10.1103/PhysRevLett.126.065702.
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
2021-02-10
As abundant and widespread bees, it is common to see both bumble bees and honey bees foraging on the same flower species during the summer, whether in Britain or many other countries.
Yet researchers at the Laboratory of Apiculture and Social Insects (LASI) at the University of Sussex, have found that different bees dominate particular flower species and revealed why.
By studying 22 flower species in southern England and analysing the behaviour of more than 1000 bees, they found that 'energy efficiency' is a key factor when it comes to mediating competition.
Bee bodyweight and the rate at which a bee visits flowers determine how energy efficient they are. Bodyweight determines the energy used while flying and walking between flowers, with a bee ...
2021-02-10
Space cooling already accounts for 14% of residential electricity demand in Brazil, and it is expected to increase further because of climate change.
Very few studies investigate the relationship between climate change, cooling needs, and electricity demand. In a new study in Energy and Buildings, a team of researchers from Universidade Federal do Rio de Janeiro and CMCC@Ca'Foscari - a joint program of Ca'Foscari University of Venice and CMCC Foundation - investigate how climate and income during the period 1970-2010 shaped cooling services in Brazil. This historical relationship allows projecting the resulting energy demand for cooling services across three warming scenarios: +1.5°C, +2°C, +4°C.
The study shows ...
2021-02-10
WEST LAFAYETTE, Ind. - Emerging robotics technology may soon help construction companies and contractors create buildings in less time at higher quality and at lower costs.
Purdue University innovators developed and are testing a novel construction robotic system that uses an innovative mechanical design with advances in computer vision sensing technology to work in a construction setting.
The technology was developed with support from the National Science Foundation.
"Our work helps to address workforce shortages in the construction industry by automating key construction operations," said Jiansong Zhang, an assistant professor of construction ...
2021-02-10
The findings add to current knowledge of how insects fly and keep stable in the air. They could also help to inspire new designs in small aerial vehicles like drones, which can be useful for search-and-rescue attempts and building inspection.
Our colourful sunny-day companions can glide, fly backwards, and travel up to 54 km/h when hunting prey or escaping predators - but like any flying creature, they can be thrown off balance and even find themselves upside down.
Many land-based animals like cats, and aerial animals like hoverflies, rotate themselves around a head-to-tail ...
2021-02-10
During a study with captive vampire bats at the Smithsonian Tropical Research Institute (STRI) in Panama, a young vampire bat pup was adopted by an unrelated female after its mother died. Although this observation was not the first report of adoption in vampire bats, it is uniquely contextualized by more than 100 days of surveillance-camera footage. This footage captured by STRI research associate Gerry Carter's lab at Ohio State University reveals intimate details about the changing social relationships between the mother, the pup and the adoptive mother throughout their time in captivity.
"The adoption took place after a very sad but ultimately serendipitous occurrence," ...
2021-02-10
Adopting policies that are consistent with achieving the Paris Agreement and prioritise health, could save 6.4 million lives due to better diet, 1.6 million lives due to cleaner air, and 2.1 million lives due to increased exercise, per year, across nine countries.
New research from The Lancet Countdown on Health and Climate Change published in a special issue of The Lancet Planetary Health journal highlights the benefits to health if countries adopt climate plans - Nationally Determined Contributions (NDCs) - that are consistent with the Paris Agreement aim of limiting warming to "well below 2°C". [1,2]
The countries considered in the study represent ...
2021-02-10
The notion of social distancing rose to public prominence approximately a year ago, when health officials began recommending it as a way to slow the spread of the novel SARS-CoV-2 virus. Despite the novelty of the concept among many contemporary human audiences, social distancing has considerable precedent among animals.
Writing in BioScience, Mark Butler of Florida International University and Donald C. Behringer of the University of Florida outline the role of social distancing in nature and compare it with its human counterpart. They describe numerous animals in which distancing has evolved, including guppies, chimpanzees, birds, ants, and mice, among many others. ...
2021-02-09
The capture of the first living Coelacanth, a mighty ocean predator, off the coast of South Africa caused quite a stir in 1938, 65 million years after its supposed extinction. It became known as a "living fossil" owing to its anatomy looking almost identical to the fossil record. But while the Coelacanth's body may have changed little, its genome tells another story.
Toronto scientists have now revealed that the African Coelacanth, Latimeria chalumnae, gained 62 new genes through encounters with other species 10 million years ago. Their findings are reported in the journal Molecular Biology ...
2021-02-09
Headlines like "Black Friday Shoppers Trampled in New York" and popular television shows such as "Extreme Couponing" remind us how crazy consumers can get about retail sales promotions. This enthusiasm for getting bargains has been termed "deal proneness."
Past research has indicated that, to some degree, people become deal prone through being taught by their parents. But a new paper, "Born to Shop? A Genetic Component of Deal Proneness," published in the Journal of the Association for Consumer Research, provides evidence that our genes also play a role in causing bargain-hunting enthusiasm.
To demonstrate this genetic factor, authors Robert Schindler, Vishal Lala, and Jeanette Taylor ...
2021-02-09
Washington, DC-- New research led by Carnegie's Yingwei Fei provides a framework for understanding the interiors of super-Earths--rocky exoplanets between 1.5 and 2 times the size of our home planet--which is a prerequisite to assess their potential for habitability. Planets of this size are among the most abundant in exoplanetary systems. The paper is published in Nature Communications.
"Although observations of an exoplanet's atmospheric composition will be the first way to search for signatures of life beyond Earth, many aspects of a planet's surface habitability are influenced by what's happening beneath the planet's surface, and that's where ...
LAST 30 PRESS RELEASES:
[Press-News.org] Stable armchairlike hexazine N6 ring in tungsten hexanitride