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Extraordinary Responsive Rare Earth Magnetic Materials

FWP/Project Description: 
Responsive systems, where a small change of an extrinsic thermodynamic variable, such as temperature, pressure, or magnetic field, triggers an intrinsic phase change, have both fundamental and technological significance.  Alloys and compounds that exhibit strong field-, temperature-, or pressure-controlled reactions, tunable by chemistry, crystallography, and processing, provide broad benefits to energy-related applications, such as sensors and smart materials, and materials for energy conversion, generation, and utilization devices.  Responsive materials, therefore, have the potential to make transformative changes that can be used to help meet our Nation’s future energy demands.  Conventional (and strong) stimuli are temperature and pressure, but a magnetic field is weak and often an underappreciated trigger, whose role in initiating strong changes in solids is much less understood.  Knowledge of the mechanisms delivering minor-stimulus driven phase change that is then followed by a major perturbation of properties is crucial for guiding the discovery of new materials, and is the focus of this research.  Our goal is to uncover the underlying electronic, atomic and microscopic interactions that result in an extraordinarily strong coupling of the magnetic and crystal lattices in chosen model systems representing rare earth-based intermetallic materials.  Development and validation of phenomenological models of transformations that range from magneto-volume to magnetic-martensitic is one of our prime objectives.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Innovative & Complex Metal-Rich Materials

FWP/Project Description: 
This project strives (i) to uncover and ultimately design new families of intermetallic phases; (ii) to understand the factors that stabilize both new and known metal-rich phases by combining exploratory synthesis and temperature-dependent structure determinations with electronic structure theory; and (iii) to establish structure-property relationships for complex metal-rich materials as related to both practical as well as fundamental issues, e.g., thermoelectric, magnetocaloric, catalytic, and magnetic behavior. Targeted compound classes include, but are not limited to, Hume-Rothery types, polar intermetallics, quasicrystalline and approximant phases, and complex metallic alloys of transition metals.  Significant focus includes (i) compounds involving reduced environments for elements of the late 5th and 6th period transition elements (Pd, Pt, Ag, Au), which offer filled d-bands and relativistic enhancements of chemical bonding; (ii) Li-rich intermetallics, taking advantage of Li’s dual role of both an active as well as an electronegative metal in chemically reduced environments; and (iii) 3d metal systems grown in reactive and eutectic fluxes. 

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Metamaterials

FWP/Project Description: 
Many of the technologies that underpin our economy and enable our standard of living depend on advanced materials. Therefore, the engine for progress in many scientific disciplines is the discovery and understanding of new materials. Metamaterials are novel artificial materials that enable the realization of innovative properties unattainable in naturally existing materials. This research project will explore the theoretical understanding, analysis, development, fabrication, and experimental characterization of metamaterials, and investigate their feasibility for applications. In view of the complexity of electromagnetic interactions in metamaterials, state-of-the-art computational techniques to understand these materials, and collaboration with experimentalists to fabricate and characterize them, are essential. Finding and understanding mechanisms that minimize loss and increasing the operating frequency will be critical for future applications, such as solar energy harvesting and biomedical/terahertz imaging. We will develop new 3D nanofabrication techniques such as direct laser writing and experimentally realize dynamic and tunable metamaterials employing nonlinear and gain materials. Finally, we will characterize the physical properties of metamaterials and develop unique optical characterization techniques.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Magnetic Nanosystems: Making, Measuring, Modeling and Manipulation

FWP/Project Description: 

The scientific goal of this effort is to investigate pathways that connect quantum mechanical mechanisms governing nano-scale magnetism with macroscopic magnetic properties emerging as the system size increases from nano- to macro- length scales. The focus ranges from low-dimensional (confined and restricted geometries) magnetic systems to homogeneous systems exhibiting magnetic texture, from modeling to fabrication, measurement and manipulation. The key goals are to examine effects of quantum confinement and reduced dimensionality in magnetic nano- and meso-scale structures, study quantum coherence and spin coupling to the environment, investigate charge and spin currents in topologic insulators and examine out of equilibrium dynamics of quantum magnetism in these systems. Advanced experimental probes, such as novel optical magnetic field sensor based on nitrogen–vacancy (NV) centers in diamond (NV-magnetoScope) and spin-polarized scanning tunneling spectroscopy (SP-STM) are used to map magnetic and electronic properties, while x-ray magnetic circular dichroism and ultra-fast magneto-optical spectroscopies provide information on element-resolved local moment and non-equilibrium charge and spin dynamics, respectively.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Novel Materials Preparation & Processing Methodologies

FWP/Project Description: 
The growth, control and modification of novel materials in single crystal and polycrystalline form, represent a national core competency that is essential for scientific advancement within and across traditional disciplinary boundaries, and are critical components of the Basic Energy Sciences’ mission. In support of this mission, the Novel Materials Preparation and Processing Methodologies FWP focuses on developing synthesis protocols for energy-relevant materials that contain volatile, reactive or toxic components such as the rare earth metals, Mg-based and RE containing thermoelectric alloys and Fe-As based superconductors.  The objective of Novel Materials is to advance the ability to synthesize and characterize high purity, high quality materials, primarily in single crystal form; to quantify and control processing-structure-property relationships between chemical inhomogeneities and structural defects and  functionality of highly responsive materials; to develop unique capabilities and processing knowledge in the preparation, purification, and fabrication of metallic elements and alloys. Single crystals are often required to achieve scientific understanding of the origin of various phenomena, whether from intrinsic or extrinsic origins, to elucidate its properties as well as to evaluate a material’s full functionality.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Photonic Systems

FWP/Project Description: 
Since ~1990, the Ames Laboratory has conducted pioneering development and studies of 3D photonic crystals (PCs), developed forefront organic light-emitting diodes (OLEDs) and procedures for characterizing them, and conducted pioneering optically detected magnetic resonance (ODMR) studies on organic semiconductors and OLEDs. PCs, artificial periodic dielectrics or metallic structures, have revolutionized control and manipulation of photons, similar to the control of electrons in semiconduc-tors. Photon diffraction by PCs has opened new vistas to control spontaneous emission, chemical reactions, optical communications, sensing, energy-efficient lighting, displays, and, in particular, solar cells. In parallel, OLEDs and organic electronics are developing rapidly, with particular relevance for solid state lighting. These research areas are combined into four interrelated tasks that will be performed in the next three years. Besides continuing studies in each of these areas, we will use our vast expertise to enhance light emission from OLEDs, thereby combining the PC expertise with (organic) light-emitting structures. We will explore new functionalities of PCs, including lasing and non-linear effects and utilize low-cost methods to design and fabricate large-area PC and OLED structures relevant to energy-related applications. In close relation to ODMR, we will also explore organic spintronics. There will be a close synergy between theory, simulation, fabrication, and experimental studies in these interrelated tasks.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Structures and Dynamics in Condensed Systems

FWP/Project Description: 
The research effort proposed here entails bringing simulation methods together with theory and critical experiments to investigate structural selection dynamics in highly driven systems. Building on our past efforts aimed at understanding the structure and properties of highly undercooled liquids and glasses, the structural dynamics of solidification and devitrification, and the fundamental behavior of interfaces, we are developing a research program that is focused on the multi-scale structural dynamics of metallic liquids, glasses, and crystalline phases under far-from-equilibrium conditions. By exploring this realm of material dynamics in earnest, we aim to open vast untapped domains of materials structures and physical behaviors, with an equally broad scope of potential functionality in magnetic, electric, elastic, thermal, and optical properties, and the critical coupled-response behaviors that may be strongly influenced by using far-from-equilibrium conditions to influence phase selection, crystallographic orientation, polycrystalline scale and texture, multiphase architectures, interface structure, solute distribution, and defect concentrations.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Surface Structures Far-from-Equilibrium

FWP/Project Description: 

The emergence of novel properties in nanostructures can be related to various factors, important ones being electron confinement and lower atom coordination. The goals of this FWP are two-fold, first to grow epitaxially controllable nanostructures and second to use their novel, selectable properties on several technologically important problems. Achieving these goals it is also essential to find ways to tune atomistic processes (diffusion, adsorption) and use them to grow  perfect nanoscale patterns easily and in short times. Such studies have been carried out in several specific systems. Understanding metal growth on graphene, graphite and other carbon coated substrates is one of the areas of interest because graphene based devices require stable metal contacts of low electrical resistance. Novel graphene properties can emerge after metal intercalation. Robust ways were found to speed up adatom diffusion, from the electric field generated in regions of different workfunction on metal islands or when 2-dimensional metallic overlayers become extremely mobile after compressed to densities higher than their crystalline densities. Understanding the growth mechanism for defect-free nanostructures with high and tunable aspect ratios on carbon coated surfaces is relevant for magnetic and optoelectronic applications.

See Tringides Group and Thiel group web pages for more information.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Development of an AccuTOF-DART™ Database of Potential Toxins, Drugs and Other Substances for Use by Forensic Laboratories

FWP/Project Description: 

This project has three phases.  The first will seek to determine the needs for the database and what data already exist.  The second will work to build the database and begin to populate the database.  The third will seek to test the database in a larger population of DART-TOF users and to disseminate the database to these users.  As DART-TOF is a very new technology, the field is very dynamic, necessitating that all involved with the project be flexible and consider other as yet unknown applications and needs.

FUNDING SOURCE:

Research Triangle Institute

FOR MORE INFORMATION:

John McClelland

E-mail: mcclelland@iastate.edu

Phone: (515) 294-7948

Environmentally Benign Repair of Composites Using High Temperature Cyanate Ester Nanocomposites

FWP/Project Description: 

DESCRIPTION:

The objective of this project is to design and evaluate a new class of environmentally benign, low viscosity resins reinforced with nanosize alumina particles.  The use temperature for these resins will be high because of Polymer’s high Tg.  These repair resins will be rheologically engineered for optimum crack filling and stability for repairmen to withstand high loadings, environmental extremes, and service temperatures.

 

FUNDING SOURCE:

Strategic Environmental Research and Development Program (SERDP)

 

FOR MORE INFORMATION:

Mike Kessler

E-mail: mkessler@iastate.edu

Phone: (515) 294-3101

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