Permanent magnets are very important for technologies of the future like electromobility and renewable energy, and rare earth elements (REE) are necessary for their manufacture. The Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany, has now succeeded in identifying promising approaches and materials for new permanent magnets through use of an in-house simulation process based on high-throughput screening (HTS). The team was able to improve magnetic properties this way and at the same time replaced REE with elements that are less expensive and readily available. The results were published in the online technical journal “Scientific Reports”.
The starting point for IWM researchers Wolfgang Körner, Georg Krugel, and Christian Elsässer was a neodymium-iron-nitrogen compound based on a type of thorium-manganese crystalline structure.
“The neodymium-iron-nitrogen compound we used has better magnetic properties than current super magnets made of neodymium, iron, and boron,” explains Georg Krugel, though the material is apparently not yet stable, having only been produced in thin layers up to now.
The goal of the group Materials Modeling’s project was to identify a new permanent magnet that exhibits the same or better magnetic properties, such as strength and directional stability, as well as the required material stability. Differing atoms in the crystal structure were systematically varied across a range of values using the new HTS process.
The researchers initially replaced the neodymium atoms with other rare earth elements such as cerium, which is considerably more economical. They then substituted iron partially by transition metals like cobalt, nickel, and titanium as well as by other elements like silicon. The HTS produced 1,280 variations this way that the researchers analyzed with respect to their properties.
Concentration on material stability, strength, and directional stability of the magnetization
“We concentrated on three properties quite important for applications during our analyses of the variations in materials,” explains Krugel. The researchers first examined the stability of the material, which could be estimated from the energy of formation. The second important aspect is the maximum attainable energy product, which allows the strength of the magnet to be estimated. The energy of anisotropy, which is a measure of the directional stability of the magnetization, is also very important for the intended application. The researchers were able to identify twelve especially promising candidates from among the 1280 variations this way.
Validation with the help of existing experimental magnetic materials
The pivotal question of course is whether the calculated properties of the variations in materials created in the computer correspond to reality. The researchers therefore additionally validated them against existing permanent magnets. The results confirmed the predictive power of the model for the magnetic properties of the HTS candidates.
Besides identifying promising approaches in materials for new permanent magnets, the researchers were able to ascertain important general trends through their work. “It was evident that cerium and neodymium are better suited on the whole than samarium," according to Krugel. Cerium in particular exhibited extremely high anistropy. Among the transition metals, the researchers were able to increase the predictability of titanium’s suitability especially.
“While transition metals reduce the strength of the magnet, they increase its directional stability considerably as well," Krugel summarizes. Valid predictions can also now be made for atoms additionally incorporated into the crystal lattice. Nitrogen and carbon are better suited than boron utlilized in current supermagnets.
New kinds of magnets might be able to be made experimentally based on the predictions of the new HTS approach. Computer-aided predictions offer an avenue for industry to identify and improve materials required to have specific properties.
Körner, W. et al. Theoretical screening of intermetallic ThMn12-type phases for new hard-magnetic compounds with low rare earth content. Sci. Rep. 6, 24686; doi: 10.1038/srep24686 (2016).
http://www.nature.com/articles/srep24686 - link to publication
http://www.en.iwm.fraunhofer.de/business-units/materials-design/materials-modeli... - link to group Materials Modeling
Katharina Hien | Fraunhofer-Institut für Werkstoffmechanik IWM
Spider silk key to new bone-fixing composite
20.04.2018 | University of Connecticut
Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model
19.04.2018 | Aalto University
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy