Non-equilibrium Phase Discovery in Finite-sized Systems

#material #discovery #non-equilibrium #materials #4d-5d #magnetocrystallinity
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A wealth of new materials could be found if that pesky “equilibrium” could be avoided. Accessing these new materials could be achieved using far-from-equilibrium processing, in this case inert gas condensation (IGC). IGC is an ideal method of forming a wide variety of nanomaterials over large composition space, with excellent control over nanoparticle size. The nanoparticles formed by IGC can be isolated from each other, creating nanoscale systems that resist transformations to equilibrium (bulk) structures, both in the as-formed state and upon heat treatment. The resulting unique structures, including solid solutions in normally immiscible systems, new atomic structures (i.e., phases), and core/shell and core/frame geometries, strongly influence magnetic and other functional behavior. For example, extensive solubility of 4d or 5d transition metals into Fe or Co can enhance magnetocrystalline anisotropy. Further, novel ordered crystal structures can form from parent non-equilibrium solid solutions, providing another route to discover new materials. This presentation will cover nanoparticle formation mechanisms, the formation and magnetic properties of extended solid solubility in Co-W and Co-Mo, complete solid solution formation in Fe-Au, and ordered L12 and L10 structures in the Fe-Au system. Other systems will also be covered, including the design of core/shell and core/frame nanoparticles, further demonstrating how IGC can be used to design novel materials and structures.


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  • Date: 03 Nov 2023
  • Time: 02:00 PM to 03:30 PM
  • All times are (UTC-04:00) Eastern Time (US & Canada)
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  • 401 W Main Street, Mechanical and Nuclear Engineer
  • Richmond, Virginia
  • United States 23284
  • Building: East Engineering Building
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  • Co-sponsored by Virginia Commonwealth University, Department of Mechanical and Nuclear Engineering

  Speakers

Dr. Jeffrey Shield Dr. Jeffrey Shield of University of Nebraska-Lincoln

Topic:

Non-equilibrium Phase Discovery in Finite-sized Systems

Abstract: A wealth of new materials could be found if that pesky “equilibrium” could be avoided. Accessing these new materials could be achieved using far-from-equilibrium processing, in this case inert gas condensation (IGC). IGC is an ideal method of forming a wide variety of nanomaterials over large composition space, with excellent control over nanoparticle size. The nanoparticles formed by IGC can be isolated from each other, creating nanoscale systems that resist transformations to equilibrium (bulk) structures, both in the as-formed state and upon heat treatment. The resulting unique structures, including solid solutions in normally immiscible systems, new atomic structures (i.e., phases), and core/shell and core/frame geometries, strongly influence magnetic and other functional behavior. For example, extensive solubility of 4d or 5d transition metals into Fe or Co can enhance magnetocrystalline anisotropy. Further, novel ordered crystal structures can form from parent non-equilibrium solid solutions, providing another route to discover new materials. This presentation will cover nanoparticle formation mechanisms, the formation and magnetic properties of extended solid solubility in Co-W and Co-Mo, complete solid solution formation in Fe-Au, and ordered L12 and L10 structures in the Fe-Au system. Other systems will also be covered, including the design of core/shell and core/frame nanoparticles, further demonstrating how IGC can be used to design novel materials and structures.

Biography:

Prof. Shield received his Ph.D. in metallurgy from Iowa State University, and his B.S. in metallurgical engineering from South Dakota School of Mines and Technology.  He is currently the Robert W. Brightfelt Professor of Engineering and Chair of the Department of Mechanical & Materials Engineering at the University of Nebraska-Lincoln.  Research interests are in the general area of microstructural development in materials during processing, formation of nanostructured materials, and development of nanoscale structures for functional devices.  He has been working in magnetic materials for more than 25 years, and cluster-based materials for the past 20 years, utilizing inert gas condensation to create novel nanoparticles and nanostructures to explore the functional behavior of materials. Professor Shield has more than 140 publications in archival journals and has received numerous scholarly awards.

Address:Lincoln, NE 68588-0526, United States