U.S. Air Force Research Lab Summer Faculty Fellowship Program

U.S. Air Force Research Lab Summer Faculty Fellowship Program

U.S. Air Force Research Lab Summer Faculty Fellowship Program

AFRL/RX Wright-Patterson Air Force Base, Ohio

SF.25.06.B4279: Towards Bottom Up Meta Materials: Hetero-Assemblies of Functional Nano-Structured Hybrids and Polymers

Vaia, R.

(937) 255-9209

The ability to engineer the performance of a material system is directly related to the precision of the techniques available to prescribe the structure and arrangement of its constituents (i.e. its architecture). Many emerging technologies require organic-inorganic compositions (30-60%) and architectural refinement that challenge traditional blending concepts, as well as demanding throughput and acreage that challenge emerging high-energy lithography and deposition technologies. Demands for such films and bulk materials range from high performance dielectrics, human performance sensors, and energy storage, to plasmonics, optical metamaterials, nonlinear-optical devices, and compliant conductors.

Efforts focus on establishing the principles underlying processing-structure-property relationships through a multi-disciplinary team that combines synthesis, processing, simulation, physics and concept demonstration. The goal is to understand the factors limiting structural perfection, and thereby establish predictability between the design of the organic-inorganic building block and the properties of its resultant assembly and device. Principle interests include inorganic nanoparticle synthesis, interface modification with a focus on the biotic-abiotic, self- and directed assembly, plasmonics, electro-optical performance, mechanical adaptivity, autonomic response and process compatibility with print-to-device technologies. Techniques include polymer physics, scattering (optical, x-ray, and neutron including synchrotron radiation experiments for real-time characterization), electron microscopy, atomic force microscopy, standard linear and nonlinear optical characterization, bulk and surface spectroscopy, modeling, processing, and synthesis.

SF.25.06.B4956: Molecular and Polymeric Materials: Modeling and Synthesis

Dudis, D.S.

(937) 255-9148

Our current efforts are focused on corrosion sciences in efforts to better understand, predict, and manage corrosion and materials degradation. Various forms of soft matter display useful conductive, semiconductive, electro-optic, and nonlinear optical properties. We are interested in these materials for a variety of applications including advanced displays, fuel cells, photovoltaics, batteries, and sensors. We apply a variety of scientific disciplines to understand and develop new materials broadly defined as conductive polymers, molecular electronics, or nanomaterials. We utilize state-of-the-art computational methods ranging from correlated ab initio first principles quantum methods to classical molecular dynamics simulations to understand and design these materials. On the experimental front, we employ modern synthetic methods to prepare and characterize such materials. We also study advanced materials concepts for structural and aerospace materials, and are focusing on bioinspired concepts related to energy harvesting, transport, transformation, storage, as well as molecular based actuation. Opportunities exist to apply advanced computational chemistry and molecular modeling methodologies employing superb high-performance computing capabilities to model and understand phenomena as well as to design materials. Opportunities also exist to synthesize and characterize unique molecules and polymers, as well as supramolecular architectures, having promising electronic, optical, or structural properties.

SF.25.06.B5508: Hetero-structured Nano Materials and Its Interfaces

Roy, A.

(937) 255-9034

The innovative utilization of materials heterogeneity through efficient design of materials interface morphology, especially at the atomistic and nano scale, offers new opportunities in tailoring properties (electronic, thermal, chemical and mechanical) of materials and influencing device performance. Our emphasis is in understanding the role of interface physics at the atomic scale to tailoring properties and linking that to continuum – geared towards efficient materials design for quantum devices, memoristors, energy, and sensors. We are interested in employing meso scale modeling approaches (such as tight binding DFT, MD, etc.) for quantitative interpretation of experimental data. Integration of atomistic and meso scale is of interest for tailored materials design of multiple constituents, vacancy, point defects, and its nanostructured interface design.

SF.25.06.B5510: Durability and Damage Tolerance of Polymer Matrix Composites

Flores, M.

(937) 255-2302

Research focus is on the development of process-modeling and material behavior tools for structural polymer matrix composites to support the development of an Integrated Computational Materials Engineering approach for material design. The overall objective is the development of fundamental processing-structure-property relationships for composites through integration of analytical, numerical and experimental tools. Emphasis is placed on models that describe the fundamental behavior of the material including: (1) failure initiation and propagation that including micro and global buckling for compression loading of composites; (2) spectrum loading fatigue crack initiation and growth in composites; (3) linking processing and mechanical performance models for aerospace grade structural composites; and (4) development of analytical/numerical and testing methods for characterizing and modeling the environmental degradation of polymer matrix composites. Interest includes continuously reinforced composites manufactured from uni-directional layers as well as textile fiber morphologies (weaves and braids). Excellent facilities are available including polymer composite processing lab, thermal analysis lab, x-ray tomography, electro-optics lab and mechanical testing lab.

SF.25.06.B5511: Modeling of Time-Dependent Behaviors in Composite Materials

Hall, R.

(937) 255-9097

Needs exist to characterize the time-dependent, thermomechanical behaviors of composite materials and their constituents under the multi-faceted influences of e.g. high temperatures, intrusion of fluids, damage, and loss and modification of material properties due to reactive and manufacturing processes. Constitutive models are under development which are thermodynamically consistent and eventually suitable for finite element structural modeling. Desired solution schemes may require stability-enhancing, multiscale enrichment delivering accuracy exceeding that obtained through standard relationships between interpolants and nodal degrees of freedom. Reduced/surrogate computational models based on the previously-described physics-based models are also of interest for application to Process-Structure-Property frameworks suitable for machine learning and probabilistic assessments of data features.

SF.25.07.B0140: Growth and Characterization of Nonlinear Optical Materials

Zelmon, D.E.

(937) 255-9867

We conduct research on nonlinear optical materials and materials processing for a variety of applications including integrated optics, frequency conversion and high power lasers. Activities include optical waveguide fabrication, study of optical phenomena such as the magneto-optic and electro-optic effects, thermal effects on materials, and theoretical modeling. Recent work has focused on the development of materials for high power fiber lasers including polycrystalline YAG and rare earth sesquioxides. In addition, materials for high power optical isolators are being investigated. A wide variety of physical, chemical, and optical characterization facilities exist including interferometry, ellipsometry, two-wave mixing, waveguide propagation measurements, absorption spectroscopy, Auger spectroscopy, x-ray diffraction, photoluminescence, and wavelength conversion measurements.

SF.25.07.B0141: Fabrication of Materials for Nonlinear Optics Applications

Cooper, T.

(937) 255-9620

We are investigating the synthesis and characterization of materials for nonlinear optics applications. The systems we are studying include chromophores, nanoparticle-chromophore hybrids, quantum dots, two-dimensional materials, perovskites and photonic polymer systems. We investigate the fabrication and properties of polymer composites, molecular glasses, multilayers, metalens systems and optical structures containing these materials. We also perform investigation of excited state behavior, including flash photolysis, ultrafast transient absorption spectroscopy and emission spectroscopy. Researchers with experience in chemical synthesis, polymer engineering and optical design are encouraged to apply.

SF.25.07.B3757: Dynamic Optical Materials using Soft Matter Motifs

Mcconney, M.

(937) 255-6573

We study the structure/property relationships of a variety of materials systems, which are broadly applicable to linear and nonlinear optical materials. Emphasis is placed on utilizing the electro-optical properties of liquid crystals for a wide variety of applications, including the development of switchable diffractive optical elements using controlled phase separation of polymer/liquid crystal composites. We are examining the fundamental polymer and liquid crystal physics, which govern the morphology and subsequent electro-optical behavior of this unique class of composites. Our interests include understanding the complex balance between phase separation, diffusion, and polymerization kinetics, and how these change as a function of the starting materials and conditions. Other liquid crystal interests include new twisted liquid crystal motifs, cholesteric and cholesteric polymer films, and novel combinations of liquid crystal and polymer structures. Current interests include photo and electro-optic mixtures of cholesteric liquid crystal/polymer mixtures, polymer photochemistry, physics of polymer structures grown from surfaces, anisotropic polymerization methodologies, polymerization strategies/designs within structured media, and novel photonic thin films fabricated using plasma enhanced chemical vapor deposition techniques.

SF.25.07.B4280: Characterization of nano-optical plasmonic systems

Urbas, A.M.

(937) 255-9713

Controlling light at the sub-wavelength scale has the potential to dramatically redefine how optical devices and technologies work in addition to opening up numerous applications where control of optical interactions is useful, such as quantum information. In order to investigate nano-optical and plasmonic effects, we conduct a program focused on fabrication and characterization of photonic structures and devices. Areas of emphasis include novel materials for plasmonic systems, incorporating active materials into plasmonics and design and fabrication of plasmonic structures for new device effects. For example, two dimensional materials, nitrides and highly doped oxides show significant potential in plasmonics. These can provide unique routes to active plasmonics and nonlinear systems. As well, the exploration of materials which can expand the operating range of plasmonic systems and increase their resilience may open up new applications, not possible with noble metal plasmonic systems. Plasmonic systems with gain have the potential to become novel light sources, such as single and coherent photon sources, in addition to providing low loss optical routing. Finally, we explore the use of plasmonic devices for imaging, spectroscopy and integrated photonics. The intersection of plasmonics with these technological areas reveals gaps in the fundamental understanding of plasmonic systems and enhances technical potential by the manipulation of light at the subwavelength scale. We probe these complex and integrated systems through combinations of linear and nonlinear spectroscopy with near field and time domain techniques. Through these studies, we advance the understanding of nano-optical systems and effects while advancing application potential.

SF.25.07.B4282: Infrared Optical Material Development

Guha, S.

(937) 255-6636 x3022

Strong third order nonlinear optical performance is demonstrated by many materials in the infrared (IR), including narrow and mid-bandgap semiconductors in the bulk form, as well as thin-film coatings of various oxides. Our overall goal is to understand and optimize the nonlinear optical properties of these materials through theoretical and experimental studies involving IR laser beams in different wavelength and pulse duration regimes. Currently, the IR materials project includes the development of materials, versatile characterization of materials properties, and detailed understanding of materials properties through modeling. The materials being developed include novel semiconductor alloys in crystalline or glassy forms and thermochromic oxide thin films. A variety of laser systems are used to characterize the materials at cryogenic and ambient temperatures. The modeling effort includes semiconductor material modeling, as well as laser beam propagation modeling with the eventual goal of combining the two efforts to obtain complete information about the laser-material interaction. Laser beam propagation modeling presents challenges for fast optical systems-especially when aberration of lenses have to be taken into account-and for propagation through multiple linear and nonlinear optical elements. Development of infrared sources through nonlinear optical frequency conversion is also an ongoing activity.

SF.25.07.B5456: Surface Phenomena in the Formation of Epitaxial Plasmonic Quantum Structures

Eyink, K.

(937) 255-5710

This research focuses on the production and modelling of epitaxial plasmonic structures in conjunction with quantum III-V semiconductor structures obtained during the molecular beam epitaxial growth. In this research we are currently focusing on two different approaches ones uses semi-metallic ErAsSb layers and nanoparticles in close proximity to epitaxial quantum structures and study the interaction between plasmonic fields formed around the metallic species and the quantum structures which can alter their emission and absorption characteristics. The other is aimed at forming hyperbolic metamaterials through ALGaSb/InAsSb or SLS structures to form a hyperbolic stack whose properties are tuned through doping or optical pumping. In this work, we employ both in situ sensors (such as spectroscopic ellipsometry, desorption mass spectrometry, and reflection high energy diffraction) and ex situ characterization (such as variable angle spectroscopic ellipsometry, AFM, STM, x-ray reflectivity and in-plane x-ray diffraction). An intermediate goal is to determine the growth conditions to produce a hyperbolic metamaterial. These layers are being formed to enhance detector, emitter, and other electronic and optical structures relevant to DOD applications.

SF.25.07.B5471: Development and Characterization of Photorefractive Materials

Evans, D.

(937) 656-9059

Photorefractive materials are being studied for applications in all-optical devices where the transfer of energy from one beam to another (beam coupling) occurs through a photorefractive grating. In inorganic photorefractives, contra-directional two-beam coupling is achieved when two counter-propagating beams interfere and form a reflection grating. The use of this geometry for studying the photorefractive properties of a material has the advantage of simplicity because only one incident beam is used, while the second beam is generated by the Fresnel refection inside the material. We have also investigated photorefractive transmission gratings in hybridized organic-inorganic photorefractive materials, as well as light scattering effects in hybridized organic-inorganic photovoltaic liquid crystal cells. Ferroelectric nanoparticles have been incorporated in the hybridized organic-inorganic photorefractive materials to enhance the optical gain.

We are interested in developing and understanding the physics of bulk and hybridized materials that exhibit the photorefractive effect in the visible, near-infrared, and infrared spectral regions. Because the photovoltaic effect can strongly influence the formation of gratings in some materials, we are also interested in the electrical properties of photorefractive materials. Inorganic crystals, liquid crystals, and ferroelectric nanoparticles are being explored.

References
Carns JL, et al: Optics Letters 31: 993 (2006).
Cook G, et al: Optics Express 16: 4015, 2008
Basun SA, et al: Physical Review B, 84: 024105, 2011
Evans DR, et al: Physical Review B, 84: 174111, 2011
Basun SA, et al: Physical Review B 93: 094102, 2016.
Shcherbin K, et al: Optics Express 6: 3670, 2016.

Keywords:
Nonlinear optics; Photovoltaic effect; Hybridized-organic-inorganic-photorefractive materials; Liquid crystal light valves; Photorefractive effect; Contra-directional two-beam coupling

SF.25.07.B5509: Theory and Computation for the Design of Functional Materials

Pachter, R.

(937) 255-9689

We are exploring development of functional materials for applications in photonics and electronics, for example, materials that require specific improved optical response, provide unique behavior for quantum technologies, enable next-generation memristors for neuromorphic computing, or novel electronic sensing modalities. To enhance the capability for "real materials" design and atomic-scale control, our research focuses on developing and applying fundamental theoretical and computational materials science approaches, including multiscale modeling. The goal is to explain measured properties and predict key observables that determine materials behavior, verified experimentally, also in a device setting. Examples comprise, but are not limited to, optical excitations in finite and extended material systems, including nonlinear optical processes in low-dimensional materials, nano-plasmonics and single-photon emission; electron transfer and transport phenomena; interfacial interactions; and biological processes. Access to computing facilities is available.

SF.25.09.B0146: Probabilistic Life Prediction of High Temperature Metals

Turner, T.

(937) 255-1387

The research focus is to develop a comprehensive understanding of relevant damage initiation and accumulation mechanisms and failure of aerospace structural metallic alloys and develop next-generation validated damage evolution and probabilistic fatigue life prediction methodologies necessary for forecasting durability and reliability during service. Specific topics of interest include: (1) microstructure-sensitive probabilistic fatigue and damage tolerance models, with emphasis on life-limiting properties, (2) initiation, microstructure-scale (small) crack growth and continuum-scale (long) crack growth under service loading conditions such as fatigue, dwell-fatigue and thermal-mechanical fatigue loading, (3) 3-dimensional crack growth and advanced fracture mechanics, including microstructure-scale (small) crack growth and continuum-scale (long) crack growth, (4) high fidelity microstructure-sensitive constitutive models for use in 3-dimensional simulation of damage accumulation in actual microstructures, (5) advanced micro- and macro-mechanics experimentation including microstructure-scale deformation mapping, multi-scale (microscale, milliscale and conventional) specimen testing under uniaxial and multi-axial loading conditions, and (6) influence of surface treatments such as peening (e.g. shot peening, laser shock peening etc.) and stress concentration sites such as holes on fatigue life and damage tolerance. Models emphasizing mechanism-based approaches for reduction in uncertainty, Bayesian methods and independent validation of predictive capabilities are of interest to us. We are seeking Integrated Computational Materials Science and Engineering (ICMSE) based multi-scale approaches and models that can be used to probabilistically predict location specific properties in geometrically complex components with nominally uniform or gradient microstructures / chemistries. Specific materials of interest include, but not limited to, Titanium alloys, Nickel-base superalloys, additively manufactured metals, and functionally graded and joined metals. Specialized high temperature testing capabilities, material characterization facilities and significant computational resources are available for multi-scale experiments and computations.

SF.25.09.B0153: Modeling Structural Alloys for Aerospace Applications

Woodward, C.F.

(937) 255-9816

This research focuses on developing and applying modeling and simulation methods to explore broad aspects of metal alloy development. Target materials include, but are not limited to, high temperature structural materials such as Ni-based superalloys, refractory metal intermetallics and Ti-Al alloys. Current areas of interest include modeling plasticity at the atomic and micron scales using electronic structure, atomistic and dislocation dynamics methods. Research in this area includes size scale, chemical, ordering, solution, and precipitate effects. Also, free energy models, based on first principles methods, are used to predict phase stability and the nature and evolution of defects in these materials. This includes properties of both the liquid and solid phases and the microstructural evolution of complex metal alloys. Significant computational resources are available through the High Performance Computing Modernization Office to perform large scale calculations, analysis and visualization. Research is closely integrated with the group's 3-d characterization and micro-scale plasticity experimental techniques and the AFRL/RX characterization facility.

SF.25.10.B4301: Biomimetics: Bionanotechnology, Biosensors and Biomaterials

Naik, R.

(937) 255-8222

The interface between biology, chemistry, and materials science has motivated biomimetic approaches to fabricate novel materials and devices for optical, electronic, magnetic and sensing applications. The diverse structures and function of biomaterials offer many exciting opportunities for creating multifunctional materials. For example, combining biomolecules with abiotic components can result in the development of novel electronic and sensing platforms. We are interested in understanding the interactions between biotic and abiotic materials, bio-functionalization approaches to creating novel structures and sensors, understanding structure-property-functional relationships of biomaterials, interfacing biomaterials with electronic materials, and integrating 3-D printing techniques with biomaterials/bioinks. These fundamental studies are the foundation of many applied technology efforts for aerospace and other application areas. We use biochemical and molecular biology tools, atomic force microscopy, deposition tools, standard bulk and surface spectroscopy, modeling, processing, and other materials synthesis and characterization tools in our efforts.

Keywords: Bionanotechnology; Biomimetics; Biomaterials; Sensors: Bioelectronics, 3-D printing; Flexible Devices

References:

1. Slocik J. M. Crouse C. A., Spowart J. E. & Naik R. R. (2013) Biologically Tunable Reactivity of Energetic Materials Using Protein Cages. Nano Lett 13, 2535-2540

2. Bedford N. M., Ramezani-Dakhel H., Slocik J. M., Briggs B. D., Ren Y., Frenkel A. I., Petkov V. G., Heinz H., Naik R. R., and Knecht M. R. Elucidation of biologically programmed atomic-scale structure of nanoparticle interfaces that modulates catalytic activity. ACS Nano 2015, 9, 5082-5092.

3. Glover D. J., Giger L., Kim S. S., Naik R. R. & Clark D. S. Geometrical assembly of ultrastable protein templates for nanomaterials. Nat Commun. 2016, 7, 11771

4. Slocik, J. M, Kuang Z., Knecht M. R., and Naik R. R. “Optical modulation of azobenzene-modified peptide for gold surface binding.” ChemPhysChem 2016, 17, 3252-3259.

5. Slocik, J. M. and Naik, R. R. Sequenced defined biomolecules for nanomaterial synthesis, functionalization, and assembly. Curr. Opin. Biotechnol. 2017, 46, 7-13

SF.25.13.B1009: Intelligent Manufacturing Automation

Berrigan, J.

(937) 255-0141

The smart factory of the future is a flexible system that can self-optimize process and overall performance across a broad network, self-adapt to and learn from new conditions in real or near-real time, and autonomously run entire production processes. This topic seeks to advance machine vision, data fusion, manufacturing decision and control in the context of materials processing and manufacturing. Of particular interest are data analytics, computational modeling, knowledge graphing methods used in conjunction with materials and process monitoring to enable autonomous control at rest for process planning or in motion for process agility. Manufacturing processes of interest include, but are not limited to, direct ink write additive manufacturing, CNC machining, co-robot human-machine teaming, and automated assembly of components.

SF.25.13.B7101: Additive Manufacturing of Polymer Composites

Baur, J.

(937) 260-9415

While great attention has been focused on metal additive and thermoplastic polymer additive methods, additive printing of fiber-reinforced thermosetting composites has received much less attention. Fiber reinforced thermosetting composites represent the most widely used polymer composite for air and space structures, as well as an increasingly larger fraction of most aerospace structural systems. While automated processes like automated fiber placement has been widely studied, the new ability to affordable print complex, digitally designed structures that are not easily manufactured by traditional methods is predicted to deliver new levels of structural efficiency and multifunctional structures. New fast and alternative cure polymer resins (UV, frontal, catalyzed) also increase cure speed and eliminate the need for oven or autoclave - significantly increasing affordability. Rapid assessment of material properties statistics, when coupled with damage progression codes and validated with select mechanical testing, can help to affordably estimate the mechanical life of a composite. This research topic includes novel concepts ranging from the exploitation of new resin chemistry to the prediction of the mechanical life of structural composite or the function of a multifunctional composite – all enabled by additive printing of fiber reinforced thermosetting polymer composites. Due to local security requirements, this topic is only open to U.S. citizens.

SF.25.13.B7103: Nucleation and Growth of Carbon Nanotubes

Maruyama, B.

(937) 255-0042

Carbon nanotubes have been studied extensively beginning in the early 1990's. Their unparalleled properties make them attractive for application in composites, electronic devices, sensors, etc. However, production of nanotubes remains inefficient and expensive, and the as-produced purity is typically less than desired. Improvements in production yield, catalyst efficiency, purity and type selectivity will enhance the viability of these materials. A fundamental understanding of the mechanisms by which nanotubes nucleate and grow is pursued in order to achieve such improvements by in-situ characterization of nucleation and growth.

We are exploring rational design of catalysts for CVD synthesis of carbon nanotubes. We modify the catalyst and catalyst support and observe the resultant changes in nanotube growth. We have also developed an Autonomous Rapid Experimentation System (ARES) to increase our ability to explore this complex parameter space. We work collaboratively with different disciplines including materials science, chemistry, physics, robotics, operations research and artificial intelligence/machine learning.

SF.25.14.B1101: Investigating Allowable Values for Additive Manufacturing Polymer Matrix Composites

Flores, M.

(937) 255-2302

Additive manufactured (AM) polymer matrix composites (PMCs) is definitely a game-changing disrupting technology and the trends are clear that they will become more widely adopted in the design of an aircraft. However, in order for this material to come into fruition in the design of an aircraft sub-system, the material must be evaluated in accordance to the Aircraft Structural Integrity Program (ASIP) MIL-STD-1530. The Durability and Damage Tolerance (DADT) requirements must take into account stability, producibility, supportability, predictability of structural performance, characterization of mechanical and physical properties. The framework is quite evident and clear on the amount of engineering that is needed to satisfy the certification of the material while providing a substantial pathway to advance AM technologies further. However, according to the AFLCMC/EZ Structures Bulletin, among the most difficult challenges for AM processes is the ability to establish an “accurate prediction of structural performance” specific to DADT. Machine learning has allowed researchers to design materials via the additive manufacturing process. Topology optimization has proven to be a creative outlet during the design phase, but primarily focuses on static boundary conditions and stiffness. Although, a variety of complex geometries with varying material stiffness could be generated, the lack of DADT focused requirements ultimately precludes the ability to address feasibility studies for structural parts during the early stages of its development. The American Society of Composites seeks to further the communities knowledge on the performance of additively manufactured composites and has identified these key challenges in addressing AM composites.

· Materials Characterization (i.e. Effects of Defects, Effects of Processing, size scales )

· Limited understanding of acceptable ranges of variation

· Limited understanding of key failure mechanisms and material anomalies

· Development of capable NDI methods

SF.25.14.B8922: Computer Simulations for Design of Improved Aerospace Materials

Berry, R.

(937) 255-2467

Research relates to current and prospective interests in design of improved materials for aerospace applications. Methodologies include electronic structure theory, chemical kinetics modeling, and molecular dynamics (including coarse-grained MD). Properties of interest include computation of transport properties (diffusion, electrochemical characteristics) and physical properties (glass transition, fragility, and density), elucidation of reaction pathways, prediction of interfacial phenomenon, and calculation of mechanical properties. More recently, emphasis has shifted to the simulation of bio-inspired materials as a function of pH, ionic strength and peptide/nucleotide sequence and structure. Projects of interest are described below:

(1) Classical and coarse-grained molecular dynamics are being conducted to simulate the assembly and function of biopolymers. Knowledge gained from these studies will be used to produce both biological and bio-inspired materials with tailored mechanical properties for a variety of Air Force applications, including structural components and templates for materials processing. For example, Nereis virens jaw protein 1 (Nvjp-1) is a protein that confers differential hardness as a function of ionic species and concentration. Hydrogels incorporating Nvjp-1 have been engineered that exhibit dramatic contraction and hardening on exposure to zinc. Our simulations aim first to predict the native structure of this highly disordered protein. Structure in hand, we seek to characterize molecular behavior, specifically the nature and location of metal-coordinated interactions and the effects of variation in pH and ionic concentrations on those interactions.

(2) Molecular dynamics simulations are being employed to evaluate the modulus, strength, and fracture toughness of polymers and composites. Automating the incorporation of quantum mechanical simulations as needed to represent bond rupture and subsequent reactions in these composites will provide an advanced framework for evaluating physical and mechanical properties in these materials at the most fundamental levels. This project is in conjunction with ongoing experimental measurements and micromechanics calculations.

(3) Atomistic simulations are being used to explore functional applications of biological macromolecules, from biosorption of valuable metals to enzymatic degradation of environmental pollutants. Subsequent analysis of properties emerging from modeling will be used to create predictive models for use in Air Force applications.

Keywords: Quantum mechanics (DFT); Classical molecular dynamics (all-atom and coarse-grained); Development of hybrid QM-MD techniques; Mechanical properties of polymer composites, assembly and structure-function relationships of bio-inspired materials; Biosorption; Biopolymers; Biodegradation

US citizenship required.

SF.25.16.B0001: Surface and Interface Control of Gallium Alloys for Integrated Stretchable Electronics

Tabor, C.

(937) 255-9184

Abstract: Gallium liquid metal alloys (GaLMAs) are room temperature fluidic conductors that can be confined to microchannels to explore flexible and stretchable electronics as well as reconfigurable agile RF electronics. The major hurdles to implementing these GaLMA materials are two-fold, controlling (1) the spontaneously forming oxide skin on the liquid alloy and (2) the reactive nature of the liquid alloy with nearly every metallic electrode material. To overcome these limitations, controlling the surface chemistry of the liquid alloys in critical and identifying electronic materials that functionally interface well with the GaLMA without reacting with them are critical issues to address. Exploring these relationships through modeling, fabrication, characterization, and processing developments is an area where extensive research is being conducted. Novel additive manufacturing techniques such as aerosol jet and inkjet among others can contribute to proper control over the surface and interface chemistry of the GaLMA materials.

SF.25.16.B0002: Damage Tolerant Multifunctional Polymer Composites

Nepal, D.

(937) 255-3232

Efficient materials design and development of tools for their damage prediction are crucial for multifunctional composites. Biomimetic design has opened up avenues for achieving extraordinary combinations of toughness and strength, similar to natural composites, although natural composites still surpass these properties. Key challenges include lack of understanding of the failure mechanisms in such composites and the influence of size, shape, and orientation of the nanofiller on toughening. There are still open questions about chemical structure and morphology around the interphase region and its influence on the mechanics. Overcoming these challenges requires careful design and a multidisciplinary approach combining synthesis, processing, characterization (across scales), and multiscale modeling. We are interested in understanding the failure mode from the nano- to higher scales, and the underlying processing structure-property relationship. Key interests include the biomimetic design of hierarchical structures; elucidating the fundamental principles of the underlying fracture mechanism based on chemistry and shape/size/distribution of the nanofillers; investigating corresponding electrical and optical properties; and establishing techniques to predict failure using molecular and mesoscale mechanics modeling. Techniques include bulk and surface spectroscopy, high-resolution X-ray micro-computed tomography, nanoscale chemical/physical/mechanical mapping, atomic force microscopy, electron microscopy, in-situ testing, and multiscale modeling.

Keywords: Biomimetic; Nanocomposite; Nanoscale imaging; Polymer; Mechanical properties; Spectroscopy; Fracture mechanics; Electro-optical properties; Multiscale modeling;

SF.25.16.B0003: Microbial Contamination of Materials: Microbially Influenced Corrosion and Biodeterioration

Kennedy, J.

(937) 255-9987

Microbially Influenced Corrosion (MIC) is defined as corrosion that is caused or exacerbated by microorganisms (bacteria, fungi). It is often facilitated by microbial biofilms--communities of microorganisms that associate with a material. These microorganisms attack the material through the production of enzymes and metabolites. The risk and rate of MIC is driven by a combination of the composition of the microbial community, the chemistry of the material, and the environmental conditions under which the microorganisms persist, which in turn drive their metabolic processes. Our laboratory examines how degradative processes are influenced by microbial physiology, microbial community dynamics and spatial-temporal relationships within biofilm communities. We use molecular, genetic, biochemical, bioinformatics, microscopic and spectroscopic tools to characterize microbial biofilms and determine their effects on materials. These fundamental studies are the foundation of many applied technology efforts for aerospace and fuel systems management, which include detection and mitigation of MIC and biofouling.

Keywords: Microbially influenced corrosion, biofilms, biodeterioration, biofouling, microbial detection

Eligibility: Open to U.S. citizens only.

References:

Hung, CS, S Zingarelli, LJ Nadeau, JC Biffinger, CA Drake, AL Crouch, D Barlow, JN Russell Jr. and WJ Crookes-Goodson. Carbon catabolite repression and Impranil degradation in Pseudomonas protegens strain Pf5 (2016) Applied and Environmental Biology. doi: 10.1128/AEM.01448-16

Barlow, DE, JC Biffinger, AL Cockrell-Zugell, M Lo, K Kjoller, D Cook, W K Lee, PE Pehrsson, WJ Crookes-Goodson, C-S Hung, LJ Nadeau, JN Russell Jr. The importance for correcting for variable probe-sample interactions in AFM-IR spectroscopy: AFM-IR of dried bacteria on a polyurethane film (2016) Analyst. 141(16):4848-54

Biffinger, JC, DE Barlow, A Cockrel, K Cusick, J Hervey, LA Fitzgerald, LJ Nadeau, C-S Hung, WJ Crookes-Goodson, and JN Russell, Jr. (2015) The applicability of Impranil-DLN for gauging the biodegradation of polyurethanes. Polymer Degradation and Stability. DOI: 10.1016/j.polymdegradstab.2015.06.020.

Mansfield, E, JW Sowards and WJ Crookes-Goodson. (2015) Findings and Recommendations from the NIST Workshop on Alternative Fuels and Materials: Biocorrosion. Journal of Research of the National Institute of Standards and Technology. http://dx.doi.org/10.6028/jres.120.003.

Biffinger, JC, DE Barlow, RK Pirlo, DM Babson, L Fitzgerald, S Zingarelli, LJ Nadeau, WJ Crookes-Goodson, and JN Russell, Jr. (2014) A direct quantitative agar-plate based assay for analysis of Pseudomonas protegens Pf-5 degradation of polyurethane films. International Biodegradation & Biodeterioration. 95: 311-319.

Crookes-Goodson, WJ, CL Bojanowski, ML Kay, PF Lloyd, A Blankemeier, JM Hurtubise, KM Singh, DE Barlow, HL Ladouceur, DM Eby, GR Johnson, PA Mirau, PE Pehrsson, HL Fraser, and JN Russell, Jr. (2013) Impact of culture medium on the development and physiology of Pseudomonas fluorescens biofilms on polyurethane paint. Biofouling 29(6): 601-615. DOI:10.1080/08927014.2013.783906

SF.25.17.B0001: Advanced Materials for Switching Memory Devices

Ganguli, S.

(937) 255-1139

An overarching theme for this research is materials development to enable more precise control over the memristor switching properties, electrical testing results from device pairs that exhibit multi-terminal latching, and efforts towards integration of multiple devices to emulate neuron functions such as programmable spiking behavior. The ultimate goal of this research program is the realization of a memristor-based, fully non-digital, neuron equivalent that can function as a unit cell in a cellular neural network. Dense crossbar arrays of non-volatile memory (NVM) devices represent one possible path for implementing massively-parallel and highly energy-efficient neuromorphic computing systems. Different types of NVM devices – including phase change memory, conductive-bridging RAM, filamentary and non-filamentary RRAM, and other NVMs –for use within a neuromorphic computing application would be investigated in this research.

Specific research would look into synthesis by Atomic Layer Deposition and Pulsed Laser Deposition, device processing (photolithography), and device performance characterization of these NVM materials. Material characterization methods like SEM and TEM (material microstructure and morphology), spectroscopic ellipsometry, x-ray diffraction, atomic force microscopy, photoluminescence, temperature-dependent Hall-effect/sheet-resistivity, temperature-dependent current-voltage, deep level transient spectroscopy, transmission line, TDTR (Time Domain Thermo Reflectance) can be applicable to establish structure property relationships. Applicants with backgrounds in various semiconductors and their electrical and thermal characterization techniques, and in simple device processing techniques are desirable. This research program will address to Air Force needs for the next generation extreme environment survivable high power RF electronics.

SF.25.18.B0001: Programmable Materials for Morphing Aerospace Structures

Baur, J.

(937) 260-9415

We are interested in the development and integration of composites with large strain, sensing and actuating materials whose response can be programmed within the material to facilitate a shape change for an aerospace structure. This can include incorporation of embedded flow, strain, or temperature sensors, shape memory or actuating materials, and the structuring of active and passive materials to provide the intended programmed response. Compliant composites and skins which can be used in conjunction with traditional external actuation. Elastomeric or soft materials with limited temperature capability and/or mechanical integrity for insertion into a load-bearing aerospace structure are not of interest. Novel processes such as multi-material additive manufacturing or ex-situ programming of material by a spatially resolved stimulus are of interest to enable the programming of the shape change. Due to local security requirements, this topic is only open to U.S. citizens.

SF.25.18.B0002: Ultra-wide bandgap (UWBG) Materials for Electronics and Optoelectronics

Mou, S.

(937) 255-9779

The objective is to study the fundamental properties of ultra-wide bandgap (UWBG) semiconductor materials (bandgap larger than 4 eV, e.g., AlN, Ga2O3, diamond, cubic boron nitride) including electronic transport measurement, defect information, photoluminescence, capacitance spectroscopy, etc. It will also involve the fabrication of the test structures for these measurements. UWBG semiconductors have the intrinsic advantages of large breakdown voltages for high power handling, emitting deep ultra-violet light, and providing stable single photon emission at room temperature due to their large bandgaps. Fundamental studies need to be pursued to understand the basic properties of these materials due to the early stage of research and development we are at. Therefore, in this topic, we look into various ways to characterize the UWBG materials to gain important knowledge on their bandstructures, electronic transport properties, defect information, interface properties, and optical emission. The characterization techniques include but are not limited to Hall-effect measurements, voltage-current measurements, capacitance spectroscopy, photoluminescence, and optical absorption. Sample preparation and test structure fabrication will also be involved to produce the test samples. The goal of this project is to generate critical and novel knowledge to evaluate UWBG materials for the interests of AF and DoD.

SF.25.18.B0004: Laser Processing of Soft Materials and Devices

Glavin, N.

(937) 255-6977

The use of lasers to directly crystallize, functionalize, pattern and induce local surface reactions in soft materials represents an exciting processing development for future flexible devices. With this technique, materials can be processed on soft, flexible substrates by restricting the absorption of the light to the active material only and also allow sub-micron photon-matter interactions and patterning. Particular materials of interest include 2D materials, organic electronic materials, nanoparticles, and other nanomaterials for flexible sensors, transistors, and photonic devices. In-situ process diagnostics will look into kinetics of phase transformation, microstructure, and morphology of the nanomaterials undergoing laser processing. Post processing characterization will include x-ray characterization, atomic force microscopy, Raman and photoluminescence, as well as electrical testing in both the DC and RF domains. This research program will address the Air Force manufacturing and processing needs for next generation flexible electronics for man/machine communication and conformal ISR.

SF.25.18.B0005: Magnetoelectric Materials for Frequency Tunable Microwave Electronics

Page, M.

(937) 255-4671

The objectives of this research are to investigate different magnetoelectric materials and phenomena with an eye towards elucidating novel materials physics that can be used for frequency agile microwave electronics. Description: Ferromagnetic resonance (FMR) in ferro/ferromagnetic materials is a promising physical phenomena for frequency tunable microwave electronics as is indicated by the widespread use of FMR in Yttrium Iron Garnet (YIG) based frequency agile oscillators and filters. Investigating novel frequency agile driving mechanisms and approaches holds the key to paving the way towards next generation microwave electronics. Thus, we are interested in studies involves investigations into novel materials, processes and physical phenomena associated with the dynamics of magnetic materials including ferromagnetic resonance and spin waves at microwave frequencies and the ability to induce/tune such high frequency oscillations without the use of external electromagnets. Towards this aim promising topics of study include, but not limited to voltage tunable FMR, novel current FMR tuning mechanisms, anti-ferromagnetic resonance, exchange bias or dipolar bias as a means to shift, fix, or adjust FMR frequencies, acoustic-driven FMR, and/or material studies associated with composite multiferroics.

SF.25.18.B0007: High Temperature Oxidation and Environmental Resistance in Refractory Complex Concentrated Alloys

Butler, T.

(937) 255-5420

Refractory complex concentrated alloys (RCCAs) are an emerging class of alloy that have the potential to push the temperature capability of current metallic solutions. While these alloys have been shown to have higher specific strength than nickel-based superalloys at elevated temperatures, they have been limited by environmental attack. Recent work has highlighted compositions that have shown increased oxidation resistance in comparison to conventional refractory alloys, which is promoted by the sluggish oxidation of complex oxides. While this work has identified some beneficial prototype oxide structures much more fundamental work is required to deliver inherent oxidation resistance for a structural RCCA alloy. We are interested in foundational work focused on inherent oxidation of these complex systems including: understanding of oxidation thermodynamics and kinetics, identification of protective oxide products and predictive oxidation models. We are also interested in exploring the use of coatings and surface treatments to increase oxidation resistance while minimally effecting the bulk composition.

SF.25.18.B0008: Statistical and Machine Learning Methods for Nondestructive Evaluation

Sparkman, D.

(937) 255-1340

This research focuses on developing and applying statistical and machine learning methods to the area of nondestructive evaluation of aircraft materials. Of interest are development of techniques that provide new and improved capabilities for analyzing data from NDE. NDE modalities of interest include ultrasound, optical, and x-ray CT and target materials include polymer and ceramic matrix composites, and aluminum, nickel, and titanium alloys. Research in this area involves the analysis of experimental data as well as data from modeling and simulation to explore new methods for data analytics for NDE. Research in statistical models and machine learning techniques to analyze the effects of material microstructure, part and assembly geometry, and material properties on the nondestructive characterization of material state and structure is of interest. Relevant research also includes the effects of inspection parameters such as transducer size, power, frequency, positioning, and sampling rate. Development of models and techniques for solving the forward/inverse problem in NDE are of significant interest. Equipment is available including ultrasound inspection systems and x-ray CT systems for performing nondestructive evaluation experiments. High Performance Computing resources are available for simulation and analysis of experimental and model data. U.S. Citizens Eligible only.

SF.25.19.B0002: Novel Ceramic Nanostructures, Hybrid Materials, and Additive Manufacturing

Dickerson, M.

(937) 255-9147

Our work is focused on developing bottom-up synthesis strategies and advanced processing methodologies that enable the design and realization of ceramics with well-controlled and novel nanostructures. The overall objective of this research is to produce materials organized on the nano-to-macro scales for basic scientific studies and to realize ceramics with enhanced properties for Air Force applications. By elucidating basic structure/property relationships that arise through nanoscale design, structural hierarchy, synthesis, and processing we strive to improve the performance of ceramic materials and composites for low density, high temperature, and multifunctional applications. Summer faculty fellows will work with the multidisciplinary team of materials scientists, chemists, physicists, engineers, and biochemists present within AFRL to pursue revolutionary concepts in ceramic nanomaterial design and synthesis. Current research interests include the self-assembly of nanoceramic systems utilizing block copolymers, the synthesis of hybrid nanomaterials including hairy-nanoparticles, and the preparation of novel organometallic polymers such as polycarbosilanes. The development of advanced additive manufacturing methodologies (direct ink writing, multi-photon lithography, and stereolithography) and synthesis of new ceramic-bearing feed stock materials is also a major focus of our team. Biomimetic, biological, and bioinspired synthesis routes and ceramic structures are also of interest. Materials currently being studied include inorganic nanomaterials, hybrid nanomaterials, pre-ceramic polymers, dendrimer polymers, refractory ceramics, non-oxide ceramics, organometallic polymers, semiorganic polymers, hyperbranched polymers, block co-polymers, 2D materials, nanotubes, and ceramic nanocomposites. Techniques of interest include additive manufacturing and synthetic methods for the (air-free) production, purification, isolation, and characterization of organometallic polymers.

SF.25.19.B0003: Structural Ceramics for Aerospace Applications

Cinibulk, M.

(937) 255-9339

The Ceramic Materials & Processes Research Team's core focus areas center on research in the development of advanced fiber-reinforced ceramic-matrix composites (CMCs) and their constituents and in understanding how service environments degrade performance at the constituent level. Fundamental scientific issues remain to be addressed to enable the development of a full range of high-performance ceramics and ceramic-matrix composites for Air Force air and space applications. Current research focuses on investigating higher temperature nonoxide fiber and matrix constituents for enhanced durability, development of oxide fiber coatings and interface control, developing fabrication processes specifically for nonoxide composites, investigating the stability of constituents in aggressive environments, and understanding key environmental effects on constituent-level behavior that affects life in relevant service environments. Intended service environments for these composites include turbine and scramjet engines, as well as hot structures and thermal protection systems for hypersonic vehicles.

SF.25.19.B0004: Modeling, Synthesis, and Characterization of Point Defects for Quantum Technology

Bissell, L.

(937) 255-9130

Quantum technologies demand unique materials properties which depend on the specific application. For example, quantum information processing benefits from single photon sources that work at room temperature, with short excited state lifetimes. Quantum metrological applications rely on factors such as ground state electronic spins with long coherence times, optical spin-polarization effects, and electronic fine structures that are dependent on strain and electric / magnetic field interactions.

Single photon sources have been identified in systems such as diamond, silicon carbide, hexagonal boron nitride, and gallium nitride. We search for color centers that may have material properties that are more favorable than known systems for high rep-rate single photon sources, quantum sensing, and metrology. The rapid identification of such color centers and prediction of their photophysical properties would impact the existing quantum technology industry.

We theoretically model defect sites of interest with respect to physical parameters key to quantum technological applications. We use supercell and cluster approaches. Factors of interest include: absorption energy, emission wavelength, excited state lifetime, and the dependence of these quantities on electric, magnetic, and strain fields. We are also looking at ways to apply machine learning to identify new candidate defect centers.

We study novel ways to efficiently incorporate defects into diamond during synthesis, such as using rational design of defect molecules, and e-beam chemistry . Finally, we characterize the suitability of the synthesized defects for quantum technology applications using confocal microscopy, single-photon counting, magneto-optical spectroscopy, and electron microscopy.

SF.25.19.B0005: 4-D Analysis of Metallic Microstructures

Payton, E.

(937) 255-9882

The size, shape, and spatial distributions of phases and defects in a material comprise its microstructure. During thermomechanical processing, microstructures evolve in ways that affect the useful life and properties of structural metallic materials. Fast and accurate prediction of microstructures and their temporal evolution is needed for optimization of the processing routes used for producing aerospace components out of new alloys. Taking into account the micromechanisms activated by complex deformation processing phenomena (which may concurrently include grain boundary sliding, dynamic recrystallization, and precipitation of secondary phases) requires the development of new techniques for measuring microstructure morphology, topology, and statistics; for generation of representative synthetic microstructures; for running mesoscale simulations of microstructure evolution under realistic processing conditions; and for improving our understanding of the effects of deformation processing on microstructures through emerging characterization techniques. Proposals are sought that (1) have significant potential for simultaneously advancing both computational and experimental capabilities in-house at AFRL; (2) present pathways for incorporation of understanding of micromechanistic phenomena of microstructure evolution into fast-acting multi-scale models suitable for coupling with finite element simulations of thermomechanical processes; and (3) address novel alloy systems with significant potential for aerospace applications.

SF.25.19.B0006: Statistical Modeling and Data Fusion for Ultrasonic Characterization of USAF Materials

Wertz, J.

(614) 824-8280

Ultrasonic characterization of flaws in USAF-relevant material systems is a unique computational challenge. Classic analytical/semi-analytical solutions for simple flaws in homogeneous materials cannot address the micro-/macro-structural heterogeneity of advanced alloys and composites. This challenge is exacerbated by a growing need for high-fidelity ultrasonic characterization of complex micro-scale features. Meeting these demands often requires computationally expensive finite element analysis (FEA). A new approach that delivers the function and flexibility of FEA-based characterization with the speed of an analytical model is desired. Potential approaches include application of statistical models such as machine learning for interpretation of complex ultrasound data; or, fusion of ultrasound data with other nondestructive sensing methods to dramatically improve quantification of micro-scale features. Material systems of interest include titanium alloys, polymer matrix composites, and ceramic matrix composites. Equipment is available for ultrasound, eddy current, thermography, and X-ray CT testing. Access to the DoD High Performance Computing cluster for simulations and model development may be provided.

SF.25.19.B0007: Nondestructive Evaluation, Characterization, Analytics

Uchic, M.

(937) 255-0594

This topic addresses fundamental technical challenges toward reliable nondestructive quantitative materials and damage characterization, regardless of scale. The intended application of this technology is towards improved nondestructive evaluation (NDE) capabilities that are integral to the sustainment and structural integrity of USAF airframes and engines and to the qualification of new materials with tailored properties. This includes but is not limited to technologies such as electromagnetic radiation across all frequency ranges, mechanical waves (e.g., ultrasound), and thermal diffusion-based methods. Current research focuses on the following activities:

• Development and utilization of forward models for quantitative prediction and optimization of NDE methods, which, have clear potential to account for the complexity of aerospace components.

• Development and utilization inverse methods to quantify the material state from NDE data, which, have clear potential to account for the complexity of aerospace components

• Analytics and statistical methods for data discovery from NDE data

• Implementation of uncertainty quantification of NDE models and experimental methods

• Correlative analysis of NDE data with ‘ground truth’ 3D data

• Creation of new NDE methods, and miniaturization of existing methods

• Integration of robotics, spatial registration sensors, machine vision, augmented and virtual reality, autonomous control systems, and other advanced technology with NDE methods

• Capability validation of in-situ damage detection sensors (Structural Health Monitoring (SHM)) via probability of detection methods

SF.25.19.B0008: Metals Additive Manufacturing Science

Schwalbach, E.

(937) 255-9840

Rapid thermal excursions (e.g. 10^6 K/s) and repeated cycling across solid-liquid and solid-solid phase transformations are common in metal additive manufacturing processes. The consequences of these process characteristics on microstructure evolution and material performance are poorly understood, and with conventional alloys these unique processing attributes are often viewed as a hindrance rather than for their potential benefits. Ongoing efforts seek to understand the implications of these details and ultimately design and test novel processing pathways and material compositions in order to realize performance improvements. Essential to this is development of tools and methods for rapidly assessing and optimizing processing pathways, in concert with experimental efforts for validation.

SF.25.19.B0009: Organic and Inorganic Polymer Hybrids for High Temperature Composite Resins, Adhesives and Coatings

Pruyn, T.

(937) 255-1142

Our research team focuses on developing new high-performance lightweight structural materials. This includes increasing the service temperature of lightweight, processable, relatively low cost, polymer-based composite materials. Specifically, our focus is developing organic and inorganic systems that meet these processing, thermal, and mechanical needs while allowing for the possibilities of additional functionality. This includes the exploration of chemistries that incorporate organic and inorganic molecules and the design of new high temperature polymers and hybrids. Our research and ongoing projects encompasses synthesis, processing, and characterization of molecular inorganic/organic hybrids, inorganic and organometallic polymers, pre-ceramic polymers, high temperature adhesives, fiber sizings and interface coatings. We are also interested in modeling of these high temperature molecules and polymers to help drive polymer architecture design. Characterization techniques include chemical structure analysis, scattering, microscopy, spectroscopy, and thermal analysis.

SF.25.19.B0010: Materials Discovery through Machine Learning/AI and Computing on Quantum Processors

Pachter, R.

(937) 255-9689

To accelerate discovery of AF-relevant materials having a required functionality, our interest is to incorporate development and application of machine learning, materials data analysis, materials databases, as well as use of emerging quantum processors in computational and experimental materials science. For example, high throughput computation for discovery of materials with unique optical or electronic properties, such as two-dimensional materials, heterostructures or engineered nanostructures by defects, combined with the use of machine learning/AI and experimental validation, are of interest. Computing facilities are available. Development of methods for computation on quantum processors for test problems is an area of interest.

SF.25.19.B0011: Studies of Ultra-Wide Bandgap Materials for Power Electronics and RF Power Electronics Applications

Neal, A.

(937) 255-9136

The recent maturity of solid state devices based on Gallium Nitride and Silicon Carbide has increased the maximum operating power of solid state power electronics and radio frequency (RF) power electronics devices, enabling higher output powers and reduced size and weight for systems based on these devices. With the success of these materials, there is a natural motivation to search for next generation ultra-wide bandgap materials to further enhance the performance of solid state power electronics and RF power electronics. Ultra-wide bandgap materials are those with a bandgap higher than Gallium Nitride (GaN) and Silicon Carbide (SiC), whose bandgaps are 3.4eV and 3.3eV respectively. Gallium Oxide (Ga2O3), with its bandgap of 4.5 eV, and Aluminum Gallium Nitride (AlGaN), with bandgaps as high as 6.2 eV for binary AlN, are examples of candidate materials which could further improve power electronics and RF power electronics device performance due to their larger bandgaps and resulting larger critical breakdown electric fields. In order to realize practical technologies based on these materials, an understanding of their material properties and those of their heterostructures, including transport, doping, defects, dielectric interface, metal-semiconductor interface, and ohmic contacts, is essential. In addition, understanding how material growth affects these properties is also critical. Candidates should grow and/or characterize ultra-wide bandgap materials in order to evaluate and/or improve properties of interest to enable future electronics technologies based on ultra-wide bandgap materials.

SF.25.19.B0012: Multifunctional Composite Structures

Kennedy, W.

(937) 255-9987

Innovative computational and experimental approaches to material design, processing, and characterization are needed in order to transform the ways in which aerospace materials enable advanced capabilities in US Air Force vehicles. Future aerospace systems will require new materials that can satisfy multiple system requirements while lowering the overall weight of the vehicle. Composite materials are sought that combine constituents into a single material system that is manufacturable, durable, and multifunctional. The goal of this program is to determine the fundamental mechanisms that determine the properties of multifunctional material systems, and the associated constraints on the processing and performance of these materials. The materials of interest comprise polymer matrix composites with novel fillers (eg, functional nanoparticles) and reinforcements (eg, tailored fiber microstructures).

SF.25.19.B0013: Materials and Characterization for High Temperature Electronic Applications

Ferguson, J.

(937) 255-9029

Research interests include development of new and novel materials and processes for power electronics and high temperature extreme environments, thermal management and approaches to improve electronics package thermal conductivity, thermal transport at interfaces, high thermal conductive substrates and die attach materials. Multifunctional graded interfaces to achieve electrical, thermal and mechanical goals are also of interest. Additional interests include development of new and novel characterization techniques for thermal transport as well as new characterization techniques at the nano- and meso- scale for thermal and electrical properties.

SF.25.19.B0015: Enabling Tailorable Material Properties with Synthetic Methods

Baldwin, L.

(937) 904-5092

The ability to synthetically tailor the molecular structure and chemical architecture of functional materials provides an opportunity to meet many Air Force application needs. Agile synthetic platforms are desirable for research tasks related to organic sensors, adhesives, and stimuli-responsive materials. Furthermore, incorporation of these systems into flexible devices remains vital to their long term success on the battlefield. Research efforts will leverage AFRL expertise and capabilities in materials science, chemistry, engineering, and biochemistry to target human performance monitoring, wearable devices, and responsive structures. Specific areas of interest include polymer synthesis, surface functionalization and on-demand actuation for the generation of dynamic materials. Candidates will have the opportunity to partner with experimental and computational scientists with the hopes of gaining a deeper understanding of material properties and identifying soft matter materials applications that assist the Air Force.

SF.25.19.B0016: Nonlinear Optical Materials Engineering

Jones, J.

(937) 255-9106

Research Program Abstract/Content. Also, specify any security/citizenship constraints/requirements needed in order to participate in the Research Program/Topic

Abstract: Employ resonant and effective media approaches in composite systems to develop and engineer structured nonlinear optical materials with nanoscale layered dimensions. The goal is a comprehensive effort using: 1) growth of materials using physical vapor deposition (PVD), 2) characterization in situ during growth of materials, 3) ex situ characterization using surface analysis techniques such as XPS, XRD, XRR, TEM, SEM, AFM, etc. and 4) optical response quantification with optical characterization techniques such as pump-probe, and second harmonic generation (SHG).

Content: Applications involving nonlinear optical materials include for example the need of wavelength conversion for quantum information systems and can be explored, along with other material properties, by developing thin films of multilayer, or multilayer composite films. For example, nanolaminates, or materials deposited sequentially having thicknesses on the order of tens of nanometers, can be generated in-house using physical vapor deposition techniques of laser ablation and magnetron sputtering with in situ ellipsometry. Films could be individually centrosymmetric materials and superlattice like structures designed in such a manner as to realize a second-order nonlinear optical response by breaking inversion symmetry, resulting in nonlinear effects such as SHG. In Situ ellipsometry is used in conjunction with pulsed laser deposition (PLD) and magnetron sputtering (MS) for precision growth of the nanolaminates. In situ sensing techniques include an Andor ICCD with focus lens, a fiber coupled spectrometer with ICCD, and spectrometer with PMT for TOF measurements of PLD. SEM/TEM/XPS/EDS/POLARIZABILITY can be used for materials thin film characterization, and other properties such as optical characterization can be accomplished using nonlinear optical characterization techniques including second harmonic generation (SHG).

SF.25.20.B0001: High Intensity Infrared Light Matter Interactions

Liebig, C.

(937) 255-9649

The interaction of high intensity ultrafast light pulses with materials is of significant interest for Air Force applications. This interaction leads to novel phenomenological effects which can modify both the optical pulse (spectral broadening, supercontinuum generation) and the material (phase change, damage). These complex interactions have been studied in the VIS-NIR wavelength regions, but due to limited laser sources in the MIR and LWIR, there has been relatively little done across these bands. To extend the knowledge base across the IR, high intensity effects are measured and modeled. To investigate the effects the nonlinear optical properties state-of-the-art techniques are used to measure both the time resolved and time-integrated nonlinear susceptibilities over a broad spectral range (VIS-MIR). These properties can then be used to interpret and model the observed phenomenological effects caused by high intensity pulse interactions.

SF.25.20.B0002: Development of Inorganic and Hybrid Polymers and Composites for High Temperature Resins and Coatings

Monzel, W.

(937) 255-9004

In this research we seek to develop coatings and composites for use at high temperatures in oxidizing environments. The use of state-of the art organic resins are limited by oxidation at higher temperatures. In this temperature regime, metal components are traditionally used. However, the use of suitable polymeric composites would result in significant weight savings. Inorganic and hybrid (organic-inorganic) polymers may provide a viable route for lightweight, thermo-oxidatively stable materials with processing similar to traditional polymer composites. Specifically this work is concerned with carbosilane and aluminum phosphate polymers, and highly networked Alumino/Siloxo (-O-Al- and -O-Si-) systems. Example resin systems of interest include phosphate geopolymers and similar siloxane materials, including MQ/MT siloxanes and polyhedral oligomeric silsesquioxane (POSS) systems. To improve mechanical properties, hybridization with high performance organic resins may also be investigated. US citizenship required.

SF.25.20.B0003: Advanced Processing of Ceramic and Ceramic Matrix Composite Structures

Rueschhoff, L.

(937) 255-9060

New and/or advanced materials and processing techniques are required to enable the development of next generation Air Force propulsion and hypersonic components. Our focus is on fundamental structure-property-processing relationships for ceramics and ceramic matrix composites (CMCs) across all constituents and length scales. Materials of interest include ceramics and CMCs with high- and ultra-high temperature ceramic (UHTC) components that can withstand the harsh environments encountered in AF components. These materials include, but are not limited to: oxide and non-oxide based CMCs, structural ceramics with RF transparency, and fiber-reinforced UHTCs. Advancements in regards to fundamental understanding of the inherent material properties, novel processing routes, and relevant environmental characterization are desired. Additive manufacturing (AM) methods such as direct ink writing, fused deposition modeling, and stereolithography are all tools of interest for creating more complex-shaped ceramic and composites with tailorable microstructures. Additionally, exploration of process modeling and/or in-situ monitoring is beneficial in providing enhanced understanding of traditional and AM-based ceramic and CMC processing.

SF.25.20.B0004: Developing Next-Generation Multi-Functional Composites for Aerospace Applications using Multi-scale Modeling and Machine Learning Approaches

Varshney, V.

(937) 255-2568

There is an ever-changing, constant need for designing novel composite materials for aerospace applications that offer a broader gamut of multi-functionality (sensing, electrical and thermal properties, desired interfaces characteristics, adhesion, energy storage/harvesting, low density, etc.) and structural stability (mechanical behavior, stiffness or compliance, fracture toughness, high temperature stability, minimal physical aging, etc.) with an eventual goal of minimizing costs and maximizing operational performance and efficiency. Experimentally, this design space is often explored via building upon previous reported literature towards synthesizing and characterizing state-of-the-art composite materials for various applications. This opportunity seeks motivated summer fellows and their students to employ well-formalized modeling methods (quantum chemistry, molecular dynamics, coarse-grain simulations) as well as to develop new modeling methods and data-analytics/machine-learning/AI frameworks to investigate and understand structure-property-performance relationships in multi-functional polymeric matrix composites (PMCs) and ceramic matrix composites (CMCs) to a) complement experimental efforts towards better appreciation of molecular origins of structure-property-performance relationships; and b) facilitate accelerated materials’ design for next-generation multi-functional composites, geared towards aerospace applications. The summer fellows will work along with a number of AFRL (Air Force Research Laboratory) scientists and engineers towards solving complex problems associated with how molecular chemical structure influences the macroscopic properties of composite materials as well as apply data analytics tools to enhance the accuracy of computational predictions for different properties of interest.

SF.25.20.B0005: High-performance aluminum alloys with thermal stability and corrosion resistance

Krug, M.

(937) 255-1387

Current conventionally-processed aerospace aluminum alloys are highly-optimized for specific applications requiring a fine balance of mechanical performance and environmental resistance. It is recognized that significant and simultaneous gains in multiple dimensions of performance may require unconventional processing and fabrication technologies such as cold spray, additive manufacturing, or powder metallurgy. The US Air Force would benefit from these advancements in several ways. As a first example of the performance areas of interest: significant enhancement of the thermal stability of aluminum alloys with high specific strength and/or stiffness could result in fuel economy improvements by displacing higher-density alloys currently in use for engine components operating at moderate temperatures. As a second example: aluminum alloys with exceptional corrosion resistance, or corrosion-resistant aluminum-based coatings showing compatibility with common aerospace aluminum alloys could be applied to reduce the substantial sustainment burden incurred due to aqueous corrosion. As a final example: the Air Force has a strong interest in the potential benefits of aluminum alloys that are amenable to powder-bed additive manufacturing processes, and which also possessing high strength, high thermal stability, or corrosion resistance. Basic research and development in microstructural stability, solidification and processing science, and corrosion resistance of novel alloys is needed to advance alloy- and processing-technologies that ideally would combine these benefits for maximum application flexibility.

SF.25.20.B0006: Studies of Topological Insulator – Ferromagnet Structures for Radio Frequency Applications

Neal, A.

(937) 255-9136

Topological insulators, first observed experimentally in 2008, and whose theoretical development in the 1970’s and 1980’s was the subject of the 2016 Nobel Prize in Physics, are unique materials which are insulating in the bulk, but have intrinsic metallic topological states on their surface. These topological surface states result from the very large spin-orbit coupling in topological insulators, and they are intrinsic to the material, existing at any surface regardless of its orientation relative to the underlying crystal structure. Due to the large spin-orbit coupling, topological insulators have been used to generate spin-polarized currents and spin-torques in ferromagnets to which they are closely coupled. The goal of this project is to evaluate the spin-torque properties of topological insulators coupled to ferromagnets through electrical characterization techniques in order to develop topological insulator – ferromagnet structures for radio frequency applications. Candidates should characterize topological insulator materials coupled to ferromagnets via techniques including but not limited to electrical transport measurements such as angle dependent anomalous Hall effect and/or Ferromagnetic Resonance (FMR) measurements.

SF.25.20.B0007: Coupling solidification theory to fusion powder bed AM processes to mitigate defect formation and inform alloy design for AM.

Chaput, K.

(937) 255-9183

Additive manufacturing (AM) is a disruptive processing capability that enables both rapid prototyping and the ability to fabricate geometries impossible through conventional means. This pervasive group of processing technologies is expected to impact a range of AF applications including small engines, hypersonics, on-board power generation/management (DE), next generation engines, etc. to deliver abrupt increases in capability. In metal fusion processes AM processes, (e.g. Laser Powder Bed Fusion), though there are plenty of challenges limiting the ability to transition this technology including the presence of defects (cracks, porosity, strong texture, residual stress etc.), which are strongly coupled to the alloy and scan strategy used to fabricate these components. In addition, high temperature Ni and Al alloys classically identified as “unweldable” are currently limited. The inability to use these materials, which are key engineering alloys to the Air Force, has capped the components that can leverage this process. Fortunately, with an understanding of the appropriate boundary conditions of the process, there exists decades of welding and solidification theory that can be leveraged to address these defects and promote compositional space that limit their manifestation (e.g. Complex Concentrated Alloys). Work is needed to develop a foundational understanding of solidification during these fusion based processes , specifically the coupled effect of geometry and scan strategy on key solidification parameters, the manifestation of solidification based defects, and identification of material factors that drive defect formation.

SF.25.20.B0008: Flexible 2D materials for electronics and sensing

Glavin, N.

(937) 255-6977

Flexible and stretchable devices based on two-dimensional (2D) materials are known to exhibit a rare combination of high electronic, sensing, and optoelectronic performance with the ability to accommodate large amounts of strain. This unique coupling is enabled by the broad optical absorption in graphene and other 2D material systems, quantum confinement of energy carriers in the 2D plane resulting in ultrafast transport dynamics, the van der Waals bonding between the layers, and the enhanced electromechanical properties that arise due to the extreme thinness of the material. We are interested in incorporation of 2D materials on polymeric substrates through direct synthesis, laser manipulation, and transfer processes to utilize the exceptional properties of these materials for future electronics and sensors. Materials of interest include elemental 2D structure including graphene, silicene, and phosphorene, as well as transition metal dichalcogenides, hexagonal boron nitride, and emerging van der Waals materials and heterostructures. By developing effective strategies to crystalize, dope, and functionalize these materials in a controlled manner, the development of robust, strainable, and high performing flexible electronics and sensors can be realized for future Air Force applications.

SF.25.20.B0009: Engineering Biology: Bionanotechnology, Biosensors and Biomaterials

Naik, R.

(937) 255-8222

The unique and diverse functions of biomolecules and biosystems provide many opportunities in developing functional materials and devices. Manipulating the interfacial interactions between biological and abiotic materials create opportunities to design hybrid materials with functional properties. Over the past several years, we have been identifying biomolecules that interact with abiotic surfaces, understanding factors that drive the interactions and exploiting such properties in creating hybrid functional materials. Fundamental studies include understanding the interactions between biotic and abiotic materials engineering biomolecules to enable the creation of creating novel structures and sensors, and understanding structure-property-functional relationships of biomaterials. We use biochemical and molecular biology tools, atomic force microscopy, deposition tools, standard bulk and surface spectroscopy, modeling, processing, and other materials synthesis and characterization tools in our efforts.

SF.25.20.B0011: Responsive Liquid Electronics

Tabor, C.

(937) 255-9184

Abstract: Low melting point metal alloys with majority constituents such as gallium and bismuth have recently provided unprecedented intrinsic properties for flexible, stretchable, and reconfigurable electronics. Two flavors of these materials have emerged in our group; (1) bulk fluids that are pneumatically controlled within microchannels and embedded fluidic tubing to physically rewire and “reprogram” the hardware components of electronics and RF devices, and (2) colloidal embodiments whereby the liquid metal colloids are suspended in a solvent and exhibit melting point suppression, high surface area, and can be used as inks for additive manufacturing. The novel intrinsic property of these liquid metals that enables these application areas is the formation of an oxide skin on the liquid alloy, which provides a self-encasing viscoelastic shell. This shell can be controlled in thickness and composition leading to a range of new tunable responsive attributes that we are exploring in our lab.

SF.25.20.B0012: Atomistic Scale Materials Hybridization for Multifunctionality

Roy, A.

(937) 255-9034

Materials hybridization (hetero-material configuration) all the way to atomistic scale offers unprecedented opportunities for optimizing materials functionality (electronic, thermal, chemical, and mechanical) at reduced material consumption and potentially reduced materials qualification costs. Multi-material heterogeneity through efficient design of materials interface morphology, processing protocol for precise placement of atoms/molecules via appropriate processing routes are desired. Our emphasis is in integrating scale-appropriate (atomic, meso, continuum) materials modeling with processing science towards developing scalable materials processing approaches and understanding the fundamentals of materials response influencing device performance. Interest is in employing innovative materials modeling, (DFT, MD, tight binding DFT, meso-scale, continuum mechanics) to facilitate developing scalable nano-processing and manufacturing approaches, such as, printing, laser or e-beam processing. Creative material metrology in conjunction of the materials modeling is also of interest.

SF.25.20.B0013: In operando Characterization of Polymer Matrix Composites

Koerner, H.

(937) 255-9324

Current manufacturing processes of polymer matrix composites are time intensive and require special tools. Our research centers on high-temperature polymer thermosets and the understanding of processing conditions that enable robust, advanced part manufacturing processes, such as 3D Printing or resin transfer molding. Specifically, our goal is to develop and confirm advanced capabilities for relating the fundamental principles that govern processes to the evolution of micro/nanostructure, cure chemistry, filler alignment, and their effects on resulting mechanical performance. This includes probing the polymer/filler interaction using advanced characterization methods and the study of in operando structure and morphology evolution. Techniques include X-ray/Neutron scattering (including Synchrotron radiation experiments), electron microscopy, atomic force microscopy, and rheology.

SF.25.20.B0014: Microbiological Degradation of Materials

Goodson, W.

(937) 255-9159

Microbiologically Influenced Corrosion (MIC) is defined as biodegradation of metals, polymers, textiles, etc., that is caused or exacerbated by microorganisms (bacteria, fungi). It is often facilitated by microbial biofilms--communities of microorganisms that associate with a material. These microorganisms attack the material through the production of enzymes and metabolites. The risk and rate of MIC is driven by a combination of the composition of the microbial community, the chemistry of the material, and the environmental conditions under which the microorganisms persist, which in turn drive their metabolic processes. Our laboratory examines mechanisms of polymer degradation and how degradative processes are influenced by microbial physiology, microbial community dynamics, spatial-temporal relationships within biofilm communities. We use molecular, genetic, biochemical, bioinformatics, microscopic and spectroscopic tools to characterize microbial biofilms and determine their effects on materials. These fundamental studies are the foundation of many applied technology efforts for aerospace systems management, material sustainment and sustainability.

Keywords: Microbiologically influenced corrosion, biofilms, biodegradation, biodeterioration, biofouling, fungi, bacteria, enzymes, polymers, microscopy, spectroscopy

SF.25.21.B0001: Machine Learning and Statistical Methods for Accelerated Corrosion Test Methodologies

Wilson, N.

(937) 255-2222

The research will assist the USAF in addressing the $5B/yr corrosion maintenance issue through the development of advanced test protocols that will potentially shorten the development cycle for new corrosion-resistant aircraft coatings and enable predictive methodologies that will significantly reduce costs via proactive corrosion preventative measures. In particular, the research will focus on developing Artificial Intelligence/Machine Learning (AI/ML) tools that will establish a statistical link between environmental data (e.g. temperature, humidity, rainfall, etc.) and materials degradation in order to aid the advancement of real-world relevant accelerated corrosion test methodologies. Additionally, research will address the development of AI/ML tools to perform predictive analysis of large volume of field data collected at various USAF locations around the world, analyze patterns of environmental factors in an environmental combined-effects chamber and relate them to the degree of corrosion for prediction of materials degradation on USAF assets.

Participation is open to US citizens only.

SF.25.21.B0002: Metal Additive Manufacturing Processing Science

Schwalbach, E.

(937) 255-9840

Rapid thermal excursions and repeated cycling across solid-liquid and solid-solid phase transformations are common in metal additive manufacturing processes, the details of which are often tightly coupled to component geometry. The consequences of these unique processing attributes for microstructure evolution and material performance remain poorly understood and are typically viewed as a hindrance rather than for their potential benefits. Ongoing efforts seek to understand the implications of these details and ultimately design and test novel processing pathways that can spatially manipulate microstructural features such as grain size and morphology, crystallographic texture, chemical/phase inhomogeneities, defect content, and residual stresses. Essential to this is the development of methods for rapidly assessing and optimizing processing pathways to include fast-acting/surrogate process models, integration of novel microstructural prediction capabilities, and strategies to reduce problem complexity and dimensionality.

AFRL/Materials and Manufacturing

Mr. Josh Kennedy
Assistant Chief Scientist
2977 Hobson Way, B653
WPAFB, Ohio 45433
Telephone: (937) 255-9987
E-mail: william.kennedy.21@us.af.mil
Mr. Mark Groff
AFRL/RX
2977 P Street, Bldg. 653, Room 416
Wright Patterson Air Force Base, Ohio 45433-7746
Telephone: (937) 255-9836
E-mail: mark.groff.1@us.af.mil