| NSF Org: |
DMR Division Of Materials Research |
| Recipient: |
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| Initial Amendment Date: | May 28, 2015 |
| Latest Amendment Date: | May 28, 2015 |
| Award Number: | 1507233 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Birgit Schwenzer
bschwenz@nsf.gov (703)292-4771 DMR Division Of Materials Research MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | June 15, 2015 |
| End Date: | November 30, 2018 (Estimated) |
| Total Intended Award Amount: | $410,000.00 |
| Total Awarded Amount to Date: | $410,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
874 TRADITIONS WAY TALLAHASSEE FL US 32306-0001 (850)644-5260 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
95 Chieftan Way Tallahassee FL US 32306-4390 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | SOLID STATE & MATERIALS CHEMIS |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
NON-TECHNICAL SUMMARY
Advanced magnetic materials are crucial to a number of current and upcoming technologies that are critical to our nation's energy security. Among these are electric vehicles, wind turbines, magnetic refrigerators, and high-density data storage devices. The improvement of such technologies relies on our ability to discover new and optimize existing magnetic materials by developing fundamental understanding of correlations between crystal structure and magnetic behavior. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, this research project targets the exploration of materials whose magnetic properties are highly sensitive to subtle changes in the crystal and electronic structures. Such solids will demonstrate abrupt changes in the magnetic behavior upon minor external perturbations (e.g., temperature or pressure) and can offer pathways to devices that operate at lower powers and exhibit higher energy-conversion efficiencies. The project will provide training for graduate and undergraduate students in solid state chemistry, materials synthesis, crystallography, magnetism, and energy-conversion technologies. The research team will also develop a comprehensive open-access online database for strongly correlated magnetic materials. The PI has a proven track-record of involving underrepresented groups and undergraduate students in research endeavors, and will continue to maintain this practice in his research and outreach activities.
TECHNICAL SUMMARY
Itinerant magnetism provides the foundation for high-performance permanent and soft magnetic materials. This research project focuses on the investigation of two classes of magnetic materials, both of which leverage strong correlations in the electronic band structure that translates into unconventional magnetic behaviors. Ternary arsenide and boride intermetallics will be investigated vis-a-vis the sensitivity of their magnetic properties to peculiarities of crystal and electronic structures. The latter will be perturbed via judicious changes in chemical composition or application of external pressure. Both chemical and physical perturbations can induce valence fluctuations that will translate into strong changes in magnetism demonstrated by these materials. A close attention will be paid to the nature of 3d-4f magnetic exchange to formulate general expectations for the type of interlattice magnetic coupling in each group of materials. The research team will also investigate ternary selenides with low-dimensional structures that result in strong magnetic frustration. Such materials are predicted to avoid long-range magnetic ordering, thus leading to exotic quantum states, e.g., spin liquids or Haldane-gap systems. The proposed research activities will provide versatile training to graduate and undergraduate students in materials synthesis, investigation of structural and magnetic properties, and studies of the electronic band structure.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Intellectural Merit. This project has led to improved understanding of the nature and behavior of itinerant magnets - a technilogically important group of magnetic materials. By using advanced characterization techniques, such as X-ray absorption spectroscopy and neutron diffraction, in combination with theoretical methods for investigation of the electronic structure of solids, we demonstrated that the traditional electron counting schemes are inadequate for explaining the behavior of metallic (itinerant) magnets. The formal oxidation states are introduced in the very early stages of chemistry education and applied broadly to various chemical problems. Our studies show that such an oversimplified approach fails to describe the redistribution of electron density associated with structural phase transitions in metallic systems, where electronic states are strongly delocalized.
The combined experimental and theoretical approach to the investigation of magnetic materials has proven to be effective not only for understanding their structural and magnetic behavior, but also for the implementation of the "materials by design" concept. Thus, the potential of AlFe2B2 to exhibit interesting magnetic behavior was initially identified theoretically and then realized experimentally.
We also demonstrated the application of neural networks to the analysis of tens of thousands of crystal structures contained in crystallographic databases. The outcome of this analysis was the ability of the machine-learning model to predict reliably the identity of elements in specific atomic positions of crystal structures it hasn't seen before. From "learning" ability by the neural network was then extended to the prediction of new chemical compositions, which now our group attempts to synthesize experimentally.
Broader Impacts. The project activities have provided research training and education to 2 postdoctoral fellows, 5 graduate students (2 of them have already defended the PhD dissertations), and 8 undergraduate students (4 of them females and 3 minority students). In addition to the research training in the lab, the students also participated in various scientific meetings and began building their professional networks.
Our research findings have resulted in the submission of two patent applications, one of which has been already granted. The discovery of the light and inexpensive magnetic refrigerant, AlFe2B2, led to a collaboration with the BASF company.
Last Modified: 03/01/2019
Modified by: Mykhailo Shatruk
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