In a collaboration between the U.S. Department of Energy's Ames Laboratory and Northeastern University, scientists have developed a model for predicting the shape of metal nanocrystals or "islands" sandwiched between or below two-dimensional (2D) materials such as graphene. The advance moves 2D quantum materials a step closer to applications in electronics.
Ames Laboratory scientist are experts in 2D materials, and recently discovered a first-of-its-kind copper and graphite combination, produced by depositing copper on ion-bombarded graphite at high temperature and in an ultra-high vacuum environment.
Ames Laboratory and Northeastern University developed and validated a model that predicts the shape of metal nanoparticles blanketed by 2D material. The top blanket of graphene resists deformation, 'squeezing' downward on the metal nanoparticle and forcing it to be extremely low and wide.
Credit: US Department of Energy, Ames Laboratory
This produced a distribution of copper islands, embedded under an ultra-thin "blanket" consisting of a few layers of graphene.
"Because these metal islands can potentially serve as electrical contacts or heat sinks in electronic applications, their shape and how they reach that shape are important pieces of information in controlling the design and synthesis of these materials," said Pat Thiel, an Ames Laboratory scientist and Distinguished Professor of Chemistry and Materials Science and Engineering at Iowa State University.
Ames Laboratory scientists used scanning tunneling microscopy to painstakingly measure the shapes of more than a hundred nanometer-scale copper islands.
This provided the experimental basis for a theoretical model developed jointly by researchers at Northeastern University's Department of Mechanical and Industrial Engineering and at Ames Laboratory. The model served to explain the data extremely well. The one exception, concerning copper islands less than 10 nm tall, will be the basis for further research.
"We love to see our physics applied, and this was a beautiful way to apply it," said Scott E. Julien, Ph.D. candidate, at Northeastern. "We were able to model the elastic response of the graphene as it drapes over the copper islands, and use it to predict the shapes of the islands."
The work showed that the top layer of graphene resists the upward pressure exerted by the growing metal island. In effect, the graphene layer squeezes downward and flattens the copper islands. Accounting for these effects as well as other key energetics leads to the unanticipated prediction of a universal, or size-independent, shape of the islands, at least for sufficiently-large islands of a given metal.
"This principle should work with other metals and other layered materials as well," said Research Assistant, Ann Lii-Rosales. "Experimentally we want to see if we can use the same recipe to synthesize metals under other types of layered materials with predictable results."
The research is further discussed in the paper, "Squeezed Nanocrystals: Equilibrium Configuration of Metal Clusters Embedded Beneath the Surface of a Layered Material," authored by Scott E. Julien, Ann Lii-Rosales, Kai-Tak Wan, Yong Han, Michael C. Tringides, James W. Evans, and Patricia A. Thiel; and published in Nanoscale.
The research was a collaboration between Ames Laboratory and Northeastern University.
Work at Northeastern University was supported by the National Institute of Standards and Technology (NIST), a national facility operated under the U.S. Department of Commerce.
Work at Ames Laboratory was supported primarily by the U.S. Department of Energy Office of Science. This work was also supported in part by a grant of computer time at the National Energy Research Scientific Computing Centre (NERSC), a DOE Office of Science User Facility.
Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Laura Millsaps | EurekAlert!
Research shows black plastics could create renewable energy
17.07.2019 | Swansea University
A new material for the battery of the future, made in UCLouvain
17.07.2019 | Université catholique de Louvain
Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.
In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...
Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.
Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...
Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.
Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...
For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.
Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...
An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".
The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...
24.06.2019 | Event News
29.04.2019 | Event News
17.04.2019 | Event News
19.07.2019 | Physics and Astronomy
19.07.2019 | Earth Sciences
19.07.2019 | Physics and Astronomy