U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

AFRL/RX Wright-Patterson Air Force Base, Ohio

SF.25.01.B9832: Stimuli-Responsive Optical and Adaptive Materials

White, T.

(937) 255-9551

Stimuli-responsive materials are essential for the realization of “smart”, highly engineered technologies needed in aerospace and countless other application areas. Towards this end, our group is pursuing the development of novel stimuli-responsive optical and structurally adaptive materials. Topical areas currently under examination are liquid crystals, liquid crystal polymer networks (glasses and elastomers), and shape memory polymers. Novel methods of triggering responses in these materials exploit a range of stimuli including thermal, electrical, and light.

Keywords:

Liquid crystals; Liquid crystal polymers; Optics; Adaptive; Polymers; Electro-optics; Polymerization processes; Polymeric films; Photopolymerization

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: Physics of Nano and Hetero-structured Materials Response

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 physics of materials response at the atomic scale and linking that to continuum – geared towards efficient materials design for quantum devices, memoristors, energy, and sensors. We are interested in the development of innovative modeling approaches integrated together with processing and characterization. Atomistic (DFT), molecular (e.g., molecular dynamics, tight binding molecular dynamics), meso-scale, as well as continuum mechanics modeling approaches are of interest for developing multiscale computational tools for tailored materials design of multiple constituents, vacancy, point defects, and its nanostructured interface design. Creative material metrology in conjunction of the materials modeling is also of interest.

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

Przybyla, C.

(937) 255-9396

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.B.

(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 sought that are thermodynamically consistent and are eventually suitable for finite element structural modeling. Required solution schemes involve stability-enhancing, multiscale enrichment delivering accuracy exceeding that obtained through standard relationships between interpolants and nodal degrees of freedom.

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, gold nanoparticle-chromophore hybrids, quantum dots and photonic polymer systems. We investigate the fabrication and properties of polymer composites, molecular glasses, multilayers and optical structures containing these materials. We also perform investigation of excited state behavior, including flash photolysis, ultrafast transient absorption spectroscopy and emission spectroscopy. We also are interested in 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

Bunning, T.J.

(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.25.07.B6434: Materials Behavior in Operating Electronic Devices

Dorsey, D.L.

(937) 528-8739

The performance and lifetime of electronic devices are both critically dependent on the behavior of the constituent materials during device operation. High electric fields, high stress/strain fields, high current densities, high temperatures and high thermal gradients may all drive material changes that can lead to degradation in device performance and ultimately device failure. Physical mechanisms that contribute to this include diffusion of electrically active impurities, generation of carrier traps, dislocation generation and propagation, hot electron effects, and interfacial instabilities. We focus on developing models of materials behavior in operating electronic devices, and using these to predict and optimize electronic device performance and lifetime. Opportunities exist for theory and model development, as well as for characterization of materials in operating, degraded, and failed devices using microRaman and scanning probe microscopy.

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

John, R.

(937) 255-9229

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.B0150: Processing Science

Semiatin, S.L.

(937) 255-1345

Research is conducted to develop material-behavior and process-modeling tools in order to exploit the full potential of conventional metals and emerging new materials such as intermetallics, ceramics, and composites using advanced ingot metallurgy, powder, vapor, and solidification-process technology. Specifically, we develop and validate advanced capabilities for relating the fundamental laws that govern processes to the evolution of microstructure/texture and the resulting mechanical properties. We emphasize the following: (1) mathematical analyses of unit processes such as extrusion, forging, rolling, and casting; (2) development of numerical models for computer simulation; (3) material modeling to understand the material behavior response to process conditions (e.g., phase transformation, texture evolution, fracture behavior); (4) development of constitutive equations for use in numerical models; (5) physical modeling for verification of analytical models; (6) interface-property modeling to represent friction and heat transfer as a function of process variables; (7) evolution of controlled microstructures during processing; and (8) development of novel processes. Special emphasis is also placed on the development of advanced models, such as those based on crystal plasticity, cellular automata, Monte-Carlo, and phase-field techniques, for the prediction of microstructure and texture evolution during processing.

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: Additive Manufacturing of Soft, Responsive Materials and Electronics

Berrigan, J.

(937) 255-1503

Additive manufacturing (i.e., 3D printing) is a unique processing method that enables exploration of novel printable materials, structures, and packaging schemes for soft electronics. These printed electronics concepts can impact a wide variety of Air Force applications including wearable sensors for human performance monitoring, embedded sensors for structural health monitoring or communication, integrated power for autonomous operation, and resilient electronic packaging to high-G shock.

Our fundamental research interests include the design tools and materials that enable soft electronics and devices. In particular, we are exploring design tools that enable coupling of electronic device function with geometrically defined mechanical properties. Additionally, inks for 3D extrusion printing of hierarchical structures, conductive composites, responsive polymers, and low-loss dielectrics are of interest. We employ a wide range of characterization tools to determine the fundamental physical phenomena in these materials and how they impact device operation. In all these areas we use a variety of analytical techniques including x-ray diffraction, atomic force microscopy, electron microscopy, rheometry, and quasi-static mechanical testing among other techniques. In addition to experimental investigation, we are also interested in applying computational and modeling methods to accelerate developmental efforts. For example, we are exploring methods to rapidly define 3D tool paths to print self-supporting structures and subsequently determine relationships between fluid rheology and machine tool path.

SF.25.13.B7101: Additive Manufacturing of Polymer Composites 

Baur, J.

(937) 255-3622

Additively manufactured polymeric materials have been previously demonstrated and are gaining increased attention. However, these 3D printed structures remain too low in mechanical and thermal properties to be of widespread use to many Air Force applications. We are interested in polymers and processing methods capable of improving the current state of the art in thermal and mechanical properties including high temperature thermosetting polymers and composites. We are also interested in the materials and additive processing of multifunctional structures (i.e. structures with embedded devices for cure monitoring, sensing, active thermal transport, EM interaction, etc).

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.B0823: Silicon Photonics for Power Scaling of Fiber Lasers

Hopkins, F.

(937) 255-3636 x4711

Fiber lasers offer significant advantages for power scaling as compared with other laser system architectures. Many components of these systems have been developed and continue to be improved. However, components for real-time beam diagnostics utilize commercial-off-the-shelf devices from the communications area, and their performance is not ideal for high-power laser (HPL) applications. The focus of the effort is to investigate new device design approaches specifically for HPL applications. One approach is to utilize controlled Mie scattering for optical sampling to enable power monitoring and perhaps even mode analysis. A related example can be found in the demonstration of a new technique for quickly measuring the attenuation of optical fiber [F.K. Hopkins et al, “A Novel Photodiode Array for Characterizing Optical Fibers,” Applied Optics 57 (2018), 409-413]. Potential projects offer both modeling and experimental tasks. Semiconductor fabrication facilities are available. Interested individuals are encouraged to discuss possibilities with the topic author.

SF.25.14.B0916: Optoelectronics and Electronics Based on Carbon and 2D Materials

Mou, S.

(937) 255-9523

Carbon materials are unique in terms of the rich variety of allotropes (e.g., graphene, carbon nanotubes, fullerenes) in the material family. From the perspectives of optoelectronics and electronics, carbon materials have great potentials (e.g., high mobility, low cost, and large area) but have yet made substantial impacts due to various reasons. Therefore, in this topic, we will look into novel ways of utilizing carbon materials for optoelectronic and electronic applications such as infrared sensing, RF electronics, and solar energy harvest. One example is that we will apply a novel physical concept, namely plasmonics, on graphene and carbon nanotubes to investigate its potential in infrared sensing. Another route is to carefully design carbon heterostructures to tailor the optical absorption by mixing various carbon allotropes. On the other hand, materials such as transition metal dichalcogenides (e.g., MoS2, WSe2, etc.) and boron nitride have recently found research interests in their two dimensional (2D) form. They form a variety of allotropes similar to carbon and are attractive in applications of optoelectronics and electronics. It is interesting to study the heterostructures formed with various 2D materials and their allotropes. The goal of this project is to generate innovative concepts on carbon based optoelectronics and electronics for the interests of AF and DoD.

SF.25.14.B1101: Microstructure Quantification and Damage Modeling of High Temperature Continuous Fiber Reinforced Ceramic Matrix Composites

Przybyla, C.

(937) 255-9396

Research focus is the development of Integrated Computational Materials Engineering (ICME) tools for the development and design of continuous fiber reinforced ceramic matrix composites (CMCs). Specifically, current needs center on development of processing-structure-property relationships for optimization of CMCs for demanding high temperature applications. CMCs are highly desirable as an alternative to high temperature metals due to higher operable temperature regimes and lower density. The variability of the damage response due to fatigue or creep at high temperature in CMCs is dependent on variability in the predominate microstructural attributes such as fiber spacing, fiber coating thickness, distributed secondary matrix phases and distributed porosity. Primary research trusts include: 1.) Process models are needed that can predict variability in key microstructure attributes such as porosity or coating thickness distribution. Processes such as chemical vapor infiltration (CVI), chemical vapor deposition (CVD) or melt infiltration (MI) are all employed to produce CMCs, coat fibers or densify matrices. Each process has inherent strengths and weaknesses and can lead to defect populations that directly affect response variability. Models that link process and process parameters to distributed attributes in the microstructure are desired. 2.) Tools necessary to quantify microstructure variability using optical, electron, or x-ray based imaging techniques are required. Post processing of microstructure data using segmentation and feature extraction can be quite time intensive and requires significant human intervention. It is desired to employ state-of-the-art computer vision and develop automated algorithms based to detect and quantify the primary features of interest (e.g., fibers, pores, fiber coatings). Once the key attributes of interested are characterized, algorithms to construct digital microstructure models representative of the characterized materials are needed for property prediction. 3.) To predict damage response of CMCs at high temperature better physics based models are needed to capture the interplay between environmental degradation and mechanical damage. Oxidation of CMCs can be significant and better models and modeling strategies are needed to predict the rates of reaction and oxidation kinetics, particularly when cracking of the matrix under mechanical loading provides pathways for transport of oxidizing species. An overall framework is desired that can be used to predict variability in response based on the variability of the key microstructural attributes that dictate the response. Research facility provides many opportunities for specialized high temperature testing and significant computing resources to aid in any project.

SF.25.14.B1117: Uncertainty Quantification of Geometric Measurements for the Assessment of Manufacturing Variability

Sizek, H.

(937) 904-4589

The Air Force Research Laboratory is conducting research to quantify the impact of geometric variability on system and subsystem performance. Realistic distributions that describe the geometric variations found in manufactured components are required to serve as inputs to performance models. The quantification of this dimensional variation typically requires high-quantity noncontact data acquisition, data analysis techniques, and a sufficient understanding of the systematic and random errors involved. The overall objective of this research is to quantify measurement process uncertainty so that high-resolution (laser scanning, structured light, etc.) measurement repeatability and reproducibility (gauge R&R) can be distinguished from the intrinsic geometric variation of manufactured components. An emphasis is placed on conducting a phased approach to address one data acquisition system on simple geometry, followed by more complex geometries produced by multiple manufacturing processes. The Materials and Manufacturing Directorate's resources include: access to laser scanning hardware and software, access to high-quantity scanned data from various on-going AF ManTech programs, and potential access to a National Institute of Standards and Technology (NIST) effort focused on noncontact equipment correlation via repeated scanning of test artifacts. In addition, representative test articles will be provided to aid in correlating measurement process uncertainty research to system performance modeling. References: Calkins, J., (2002), "Quantifying Coordinate Uncertainty Fields in Couples Spatial Measurement Systems", Doctoral Thesis Virginia Polytechnic Institute and State University. Martinez, S., Cuesta, E., Barreiro, J., and Alvarez, B., (2010), "Analysis of Laser Scanning and Strategies for Dimensional and Geometrical Control", The International Joutnal of Advanced Manufacturing Technology, 46(5-8), pp. 621-629. Feng, H., Liu, Y., and Xi, F., (2001), "Analysis of Digitizing Errors of a Laser Scanning System", Precision Engineering, 25(3), pp. 185-191.

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, bacterial gas vesicles are hollow structures made entirely of proteins produced by marine bacteria to aid in flotation; gas molecules can diffuse in, but water cannot. Condensation of moisture inside the vesicles is prevented due to its superhydrophobic interior surface, one of the most hydrophobic known. Our investigations seek to elucidate the mechanism, selectivity and location of gas transport across the vesicle walls. The ultimate goal is to identify critical interactions and residues responsible for allowing certain gases in while keeping water out and for maintaining the stability and strength of the vesicles.

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 investigate peptides that have been experimentally identified as “good” binders to inorganic and organic surfaces. Goals include the estimation of binding constants, determination of conformational changes on adsorption and elucidation of the mechanism(s) of binding, all of which are compared with extant experimental data. Analysis of these results centers on parameters including peptide sequence, surface coverage, pH, and surface structure/roughness. Extensions of this work include investigations of bio-mineralization in order to determine the thermodynamic stability of various morphologies and particle shapes.

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; Bio-mineralization; Biopolymers.

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

Tabor, Christopher

(937) 255-9899

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

Goodson, Wendy

(937) 255-9385

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) 255-3622

We are interested in the development and integration of composites with 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 may also be of interest. But, elastomeric or soft materials with limited potential for integration 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.

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.B0003: Research on Manufacturing Variability

Turek, S.

(937) 255-9058

The Manufacturing and Industrial Technologies Division (ManTech) identifies, prioritizes and integrates Air Force industrial base requirements with program execution authority to provide advanced manufacturing processes, techniques, systems, and equipment needed for timely, reliable, high quality economical acquisition, production, and repair of Air Force systems. ManTech is interested in advancing manufacturing research to monitor, quantify, and control the impact of manufacturing variability on system and subsystem performance. Realistic distributions that describe the variations found in manufactured components are required to serve as inputs to performance models. The quantification of this variation typically requires data acquisition (e.g. high-quantity noncontact inspection, computed tomography, nondestructive inspection, process monitoring), data aggregation, and analysis techniques combined to convert data to information and to sufficiently understand the systematic and random errors involved. The overall objective of this research is to distinguish measurement process uncertainty from controllable and non-controllable manufacturing process variation. An emphasis is placed on conducting a phased approach to address one data acquisition system, followed by more complex geometries produced by multiple manufacturing processes. Proposers shall specify materials and manufacturing systems of relevance to Air Force applications from which the variability/uncertainty in data acquisition and analysis techniques may be quantified. Proposers must specify equipment and data acquisition needs, including facilities outside of AFRL to be utilized. Proposers should also specify computational models and/or software required for analysis.

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

McConney, M.

(937) 255-4052

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.B0006: Rapid Alloy Design and Screening Methodologies and Techniques for Refractory Complex Concentrated Alloys

Chaput, K.

(937) 255-9183

Refractory complex concentrated alloys (RCCAs) are a novel class of material which have been shown to display high specific strengths at temperatures much higher than that of Ni-based superalloys and superior oxidation resistance to conventional refractory alloys. Of the RCCA compositions that have been investigated, limited overlap exists between the mechanically-optimized alloys and those designed for oxidation resistance. Fortunately, the alloys that have been identified by the community to-date are but a small fraction of the potential RCCA compositional space. While this large compositional breadth allows for great potential, intelligent approaches are required to effectively identify candidate systems. We are interested in developing methodologies to rapidly navigate RCCA compositional space by designing computational and experimental techniques that allow for low-risk, but accurate assessment of the mechanical and oxidation response across a broad range of possible alloying families. This task ranges from identifying methods for rapid specimen production to foundational research to design, develop and validate techniques for quickly screening a large number of alloys. Areas of specific interest include an approach to rapidly assess an alloys ductility, elevated strength, phases, and oxidation resistance.

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) 255-4106

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, eddy current, FTIR, thermography and x-ray CT and target materials include polymer and ceramic matrix composites, Al-alloys, and Ti-Al 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 and eddy current 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.

SF.25.19.B0001: Modeling, Synthesis, and Characterization of Point Defects for Quantum Technology

Bissell, L.

(937) 255-6316

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 also study novel ways to efficiently incorporate defects into diamond during synthesis, using a microwave chemical vapor deposition reactor. 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.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: Fundamental science of advanced polymer matrix composite processing

Koerner, H.

(937) 255-9324

Continuous reinforced polymer matrix composites with high-temperature capability and excellent thermo-oxidative stability are state-of-the-art materials for lightweight parts and components of current Air Force applications. However, current manufacturing processes are time intensive and require special tools. Our research centers on high-temperature polymer thermosets, molecular inorganic hybrids and nanocomposites, and methods for light weighting and novel advanced manufacturing methods, including 3D printing. 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, and filler alignment, and their effects on resulting mechanical properties and performance. This includes probing the polymer/filler interaction physics using advanced characterization methods and the study of in-situ structure and morphology evolution during processing, such as additive manufacturing. Techniques include scattering (optical, X ray, and neutron including synchrotron radiation experiments for real-time characterization), electron microscopy, atomic force microscopy, rheology, chemical analysis (spectroscopy), processing, thermal characterization, and synthesis.

Keywords: High-temperature thermosets; Additive manufacturing; Inorganic hybrids; Nanocomposites; Scattering; Polymers; Composites; Nanomaterials; In-situ monitoring; Structure-processing-performance relationships

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: Modeling and Simulation for Ultrasonic Nondestructive Evaluation of Composite Materials

Wertz, J.

(937) 255-2718

This research focuses on the development of rapid modelling techniques for the ultrasonic inspection of inhomogeneous structural materials with complex internal features. Specific material systems of interest include both polymer and ceramic matrix composites, while internal features include ply delaminations and matrix cracks. Research in this area involves analysis of experimental data to support model validation. Bulk wave ultrasound is the preferred technique, with emphasis on collecting and exploiting information from the complete damage region. Equipment is available including ultrasound and eddy current inspection systems and X-ray CT systems for performing nondestructive evaluation experiments. Surrogate models informed by high performance computing (HPC) simulations are also of interest.

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

Uchic, M.

(937) 255-0594

This topic addresses fundamental technical challenges toward holistic Materials State Awareness—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

• development and utilization inverse methods to quantify the material state from NDE data

• application of 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 from destructive characterization methods

• 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 functionalities, 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. In addition, the use of machine learning for the design of metasurfaces, and integration of computed materials properties within autonomous experimental systems are of interest. Computation on quantum processors, as appropriate and available, for specific test problems, is an area of interest. Computing facilities are available.

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: Characterization Techniques and Materials for High Temperature and Thermal Transport in Electronic Applications

Ferguson, J.

(937) 255-9029

Research interests include development of new and novel semiconductor materials for power electronics and high temperature extreme environments. Thermal management and approaches to improve the device thermal conductivity, thermal transport at the interfaces, or external, such as high thermal conductive substrates and circuit boards. Multifunctional graded interfaces to achieve electrical, thermal and mechanical goals are also of interest. Additionally characterization of materials for electrical (conductivity, mobility, traps/defects, etc.), thermal transport (3-Omega, time domain thermal reflectance, etc.) and mechanical properties (thermal cycling, thermal shock, extreme environment) are of interest as well as new characterization techniques at the nano- and meso- scale.

SF.25.19.B0014: Modeling, Synthesis, and Characterization of Point Defects for Quantum Technology

Bissell, L.

(937) 255-6316

Research interests include development of new and novel semiconductor materials for power electronics and high temperature extreme environments. Thermal management and approaches to improve the device thermal conductivity, thermal transport at the interfaces, or external, such as high thermal conductive substrates and circuit boards. Multifunctional graded interfaces to achieve electrical, thermal and mechanical goals are also of interest. Additionally characterization of materials for electrical (conductivity, mobility, traps/defects, etc.), thermal transport (3-Omega, time domain thermal reflectance, etc.) and mechanical properties (thermal cycling, thermal shock, extreme environment) are of interest as well as new characterization techniques at the nano- and meso- scale.

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 also study novel ways to efficiently incorporate defects into diamond during synthesis, using a microwave chemical vapor deposition reactor. 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.

AFRL/Materials and Manufacturing

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