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Posted: Apr 20, 2017
Deciphering material properties at the single-atom level
(Nanowerk News) It was a big challenge and a small particle. Scientists determined the three-dimensional position of more than 23,000 atoms in a tiny iron-platinum particle with 22 picometer precision. They correlated the observed chemical order/disorder and defects in the atomic structure with magnetic properties at the single-atom level (Nature, "Deciphering chemical order/disorder and material properties at the single-atom level").
This data can serve scientists to model and design new materials whose atomic composition is tailored to obtain the desired properties.
Precise identification of the three-dimensional coordinates of iron (in red) and platinum (in blue) atoms in a tiny iron-platinum particles. (Image: Colin Ophus)
Perfect crystals are rare in nature. Much of our modern science and technology rely on materials with defects and disorder. Understanding the disorder – and its effect on material properties – are critical to designing improved materials for energy production, storage and use.
This work makes major advances in characterizing materials. It also expands our understanding of how a material’s structure and behavior are related in defected materials. Further, scientists expect this approach to find broad use in materials science, physics, chemistry, and other fields.
The ability to correlate the 3D arrangements of atoms and defects with a material’s properties and functionality is vital in designing new and improved materials for a myriad of applications.
In this research, scientists determined the 3D coordinates of 6,569 iron and 16,627 platinum atoms in an iron-platinum nanoparticle.
They used an imaging technique called atomic electron tomography to correlate 3D atomic arrangements and chemical order/disorder with material properties at the single-atom level.
They identified rich structural variety and chemical order/disorder with unprecedented 3D detail including atomic composition, grain boundaries, anti-phase boundaries (where atoms are arranged in the opposite order of the perfect, parent crystal), anti-site point defects and swap defects (where individual or a pair of nearest-neighbor atoms switch places).
A team of scientists from the University of California at Los Angeles, Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory demonstrated that experimentally measured 3D atomic coordinates and chemical species with 22 picometer precision can be used as direct input for first-principles calculations of material properties such as atomic magnetic moments and local magnetocrystalline anisotropy.
This work opens the door to determining 3D atomic arrangements and chemical order/disorder of a wide range of nanostructured materials with high precision.
It also gives researchers the ability to study material properties on the single-atom level that could transform our understanding of structure-property relationships at the most fundamental level.
Source: U.S. Department of Energy, Office of Science