“We could potentially create new materials with unusual properties that have never existed,”
By creating atomic chains in a two-dimensional crystal, researchers at Penn State believe they have found a way to control the direction of materials properties in two and three dimensional crystals with implications in sensing, optoelectronics and next-generation electronics applications.
Whether an alloy has a random arrangement of atoms or one that is ordered can have large effects on a material’s properties. In a new paper published online in the journal Nano Letters, Nasim Alem, assistant professor of materials science and engineering, and colleagues at Penn State used a combination of simulations and scanning transmission electron microscopy imaging to determine the atomic structure of an ordered alloy of molybdenum, tungsten and sulfur. They determined that fluctuations in the amount of available sulfur were responsible for the creation of atomic chains of either molybdenum or tungsten.
“We discovered how chains form in a two-dimensional alloy as a result of fluctuations in the amount of a particular precursor, in this case sulfur,” Alem said. “Normally, when we combine atoms of different elements, we don’t know how to control where the atoms will go. But we have found a mechanism to give order to the atoms, which in turn introduces control of the properties, not only heat transport, as is the case in this work, but also electronic, chemical or magnetic properties in other alloy cases. If you know the mechanism, you can apply it to arrange the atoms in a wide range of alloys in 2D crystals across the Periodic Table.”
In the case of the molybdenum, tungsten and sulfur alloy, they showed that the electronic properties were the same in every direction, but using simulations they predict that the thermal transport properties are smaller perpendicular to the chains or stripes.
“We didn’t know why this crystal forms an ordered structure, so we worked with my colleague Dr. Vin Crespi to understand the underlying physics that causes order in this crystal. Our calculations show it was the fluctuations in the third element, sulfur, that was determining how the chains formed,” Alem said.
Vincent H. Crespi, Distinguished Professor of Physics, and professor of chemistry and materials science and engineering who developed the theoretical understanding of the phenomenon, said, “Although the interior of the flake is indifferent to whether molybdenum or tungsten occupies any site in the crystal lattice, the edge of the growing crystal does care: Depending on how much sulfur is available at a given location, the edge will prefer to be either 100% molybdenum or 100% tungsten. So as the availability of sulfur randomly varies during growth, the system alternately lays down rows of molybdenum or tungsten. We think this may be a general mechanism to create stripe-like structures in 2D materials.”
Amin Aziz, who is a Ph.D. candidate in Alem’s group and lead author on the Nano Letters paper, produced the STEM imaging and spectroscopy that showed the fine atomic structure of the alloy samples and their electronic properties.
“When we are able to directly image constitutive atoms of a substance, see how they interact with each other at the atomic level and try to understand the origins of such behaviors, we could potentially create new materials with unusual properties that have never existed,” said Azizi.
A team led by Mauricio Terrones, professor of physics, produced samples of this ordered alloy by vaporizing powders of all three elements, called precursors, under high heat.
The Latest on: Atomic chains
via Google News
The Latest on: Atomic chains
- Structural insights into secretory immunoglobulin A and its interaction with a pneumococcal adhesinon May 12, 2020 at 1:33 am
Secretory Immunoglobulin A (SIgA) is the most abundant antibody at the mucosal surface. It possesses two additional subunits besides IgA: the joining chain (J-chain) and secretory component (SC). SC ...
- IAEA Project to Help Countries Tackle COVID-19 Draws €22 Million in Fundingon May 11, 2020 at 11:11 am
The IAEA is sending equipment to help countries test for the COVID-19 virus using real time RT-PCR. Package includes personal protective equipment (PPE), PCR machines, reagents and laboratory ...
- Albert Einstein's atomic bomb warning letter that 'stopped Hitler winning WW2' revealedon May 7, 2020 at 9:35 am
ALBERT EINSTEIN was the German-born theoretical physicist genius behind the theory of relativity, but he also near enough saved the world from nuclear disaster with a letter he wrote to US President ...
- Successfully measuring infinitesimal change in mass of individual atoms for the first timeon May 7, 2020 at 7:15 am
When an atom absorbs or releases energy via the quantum leap of an electron, it becomes heavier or lighter. This can be explained by Einstein's theory of relativity (E = mc2). However, the effect is ...
- The Mechanical Behaviors of Polyethylene/Silver Nanoparticle Composites: an Insight from Molecular Dynamics studyon May 5, 2020 at 2:12 am
This research uses molecular dynamics simulation (MD) to study the mechanical properties of pristine polyethylene (PE) and its composites which include silver nanoparticles (PE/AgNPs) at two AgNP ...
- Nuclear Weapons Denied: How Hitler Failed to Even Get Close to the Bombon May 4, 2020 at 6:06 pm
In fact, by the spring of 1945, when America’s massive nuclear program was reaching its culmination, the Nazi atomic program consisted of one experimental reactor in a cave in southern Germany, ...
- The Pandemic Has Made Industrial Policy Palatable Even to Republicanson May 4, 2020 at 1:00 am
Once considered taboo among conservatives, the idea of government-directed manufacturing and strategy is gaining advocates.
- United States Atomic Magnetometer Market Overview and Scope 2020 to 2025on May 3, 2020 at 8:17 pm
"The Atomic Magnetometer Market report provides a detailed analysis of the dynamic of the market with extensive focus on secondary research. The report sheds light on the current situation of the ...
- How a Tiny Widget Waylaid the World’s Biggest Science Experimenton May 3, 2020 at 5:23 pm
It was one of the smallest pieces in the world’s biggest science project that turned into the most vexing coronavirus supply-chain hurdle for Bernard Bigot.
via Bing News