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.K.

(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 electronics, sensors and energy. 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 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 and frequency conversion. Activities include optical waveguide fabrication, study of optical phenomena such as the photorefractive and electro-optic effect, and theoretical modeling. Recent work has focused on the development of materials for high power fiber lasers including polycrystalline YAG and rare earth sesquioxides. 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.M.

(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 and molecular glasses 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 and polymer engineering are encouraged to apply.

SF.25.07.B0154: Optical Properties of Semiconductors

Brown, G.J.

(937) 255-9854

This research focuses on the infrared (IR) absorption and optical properties of nanoscale semiconductor heterostructures such as quantum dots, quantum wires and superlattices.. Materials under investigation include InAs quantum dots,and superlattices based on III–V compounds, such as InAs/GaInSb and InAs/InAsSb.

The epitaxial heterostructures are grown using molecular beam epitaxy. Designing and testing the unique properties of these nanoengineered materials is a key focus of the program. Therefore, theoretical work on modeling the properties of new materials is included under this topic. Of interest is improved understanding of optimizing the optical absorption processes, tailoring the absorption bands, and enhancing electrical charge transport of photoexcitied carriers. Understanding the interfaces between the various materials in the heterostructure plays an important role in the materials development process. Typically the materials under study are for infrared detection.

Expertise in optical characterization techniques such as photoluminescence, UV/Vis/IR absorption, or photoconductivity is relevant to testing the optical properties of the materials. There is a Cary 5000 UV/Vis/near IR spectrometer, a Varian FTS 6000 mid-IR to VLWIR spectrometer, and a Bruker FTIR photoluminescence spectrometer in-house. All of these systems are capable of measurements at cryogenic temperatures. There are many other facilities in-house that can also be utilized in the study of these materials, such as HRTEM, HRXRD, SEM, AFM, STM, XPS, SIMS, Auger spectroscopy, and Hall Transport measurements.

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.B5104: Materials for Integrated Electronic and Electro-Optic Circuits 

Grote, J.G.

(937) 255-9776

Our research focuses on the development of bio-organic materials and fabrication processes for high-speed, low operating power, high efficiency, small size organic-based integrated electronic and photonic devices, including organic field effect transistors (OFETs), organic light emitting diodes (OLEDs, organic light emitting diodes (OLETs), organic electro-optic (EO) modulators, organic photovoltaics (OPVs), polymer capacitors and electromagnetic (EM) shielding. In-house research involves investigation of bio-organic based semiconductor and gate dielectric materials for FETs and OLETs, blocking, transport and active layers for OLETs, OLEDs and OPVs, cladding and active layers for EO modulators, high K, high breakdown dielectric materials for capacitors and high electrical resistivity EM shielding materials. Work includes (1) materials processing; (2) electromagnetic, optical and nonlinear characterization of materials; (3) new fabrication methods and processes; (4) computer modeling and simulation; and (5) integration, packaging, and manufacturing processes. Materials of interest include deoxyribonucleic acid (DNA), silk and nucleobases. Close collaboration with other Air Force research directorates is a high priority.

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

Eyink, K.G.

(937) 255-5710

This research focuses on the modification of quantum III-V semiconductor dot structures obtained during the molecular beam epitaxial growth through nano-patterning of surfaces and self assembly. Typically, growth of III-V semiconductor dots are formed through the self-assembly process, which is rooted in the strain driven nucleation and growth of the three-dimensional epitaxial crystals. The goal of this research is to determine the extent to which nano-patterning can be used to control the location and size distribution of quantum dots(QDs) and wires and also to the extent that dissimilar materials can be integrated using strain. We are currently focusing on the ability of strain driven epitaxy to align semi-metallic ErAsSb nanoparticles (NP) with InGaAs QDs. 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 vertically stacked layers of ErAs NP to InAs QDs. 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.R.

(937) 255 4552

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, polymers, liquid crystals, and ferroelectric nanoparticles are being explored.

References

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

Keywords:

Nonlinear optics; Photovoltaic effect; Hybridized-organic-inorganic-photorefractive materials; 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, including nanoscale clusters and particles, one- and two-dimensional materials, biomaterials, and hybrid (bio)organic-inorganic materials. Our research focuses on developing and applying fundamental theoretical and computational chemistry and materials science approaches, including multiscale modeling, in order to enhance the capability for "real materials" design and atomic-scale control. The goal is to explain measured properties and predict key parameters that determine materials behavior, also in a device setting. Examples of theory and computation comprise, but are not limited to, optical excitations in finite and extended material systems, including nonlinear optical processes and nano-plasmonics; electron transfer and transport for electronic sensory function; (bio)organic-inorganic interfacial interactions; biological processes; or Raman characterization of low-dimensional materials. Access to high performance 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: Probabillistic 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 process simulation on computers; (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) 255-9717

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, development of deposition techniques for 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

Eligibility: Open to U.S. citizens only.

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. Kim S. S., Hisey C. L., Kuang Z., Comfort D. A., Farmer B. L. & Naik R. R. (2013) The Effect of single wall carbon nanotube metallicity on genomic DNA-mediated chirality enrichment. Nanoscale 5, 4931-36

3. Dickerson M. B., Lyon W., Gruner W. E., Mirau P. A., Jespersen M. L., Fang Y., Sandhage K. H. & Naik R. R. (2013) Unlocking the Latent Antimicrobial Potential of Biomimetically Synthesized Inorganic Materials. Adv. Funct. Matls. DOI: 10.1002/adfm.201202851

4. Kuang Z., Kim S. N., Crookes-Goodson W. J., Farmer B. L. & Naik R. R. (2010) Biomimetic Chemosensor: Designing Peptide Recognition Elements for Surface Functionalization of Carbon Nanotube Field Effect Transistors. ACS Nano. 4, 452-458

5. Slocik, J. M. & Naik, R. R. (2010) Probing peptide-nanomaterial interactions. Chem Soc. Rev. 39, 3454 – 3463

SF.25.10.B4959: Additive manufacturing using oxide glasses 

Goldstein, J.T.

(937) 255-9785

In-house experimental research is currently being conducted in the area of additive manufacturing of optical structures using oxide glasses and ceramics, for both gradient-index optical elements and multi-layered optical waveguides.  Methods being investigated include laser sintering of an oxide-glass powder-bed, laser-sintering of fed powder, high-precision and high-throughput ink-jet printing and aero-jet printing of oxide powder inks with both in-line and subsequent annealing, as well as in-furnace building by powder-feed.  Complementary modelling efforts exploration of the thermal processing characteristics including the diffusion of the different glass types during thermal processes, and modeling the optical properties of the materials and proposed structures.  All facilities and equipment necessary for conducting both the experiments and the modelling are present in-house.

SF.25.13.B1009: Flexible Electronics for sensing, Commuincation, and Power 

Berrigan, J.

(937) 255-1503

Flexible electronics offer the potential to impact a wide variety of Air Force applications by enabling conformal and stretchable form factors, reducing component weight and providing increased durability.  Applications can include wearable sensors for human performance monitoring, embedded sensors for structural health monitoring, integrated thin-film power for autonomous operation, and resilient electronics among others.  Our research focuses developing materials and processes to enable these applications such as flexible, stretchable substrates, novel thin-film or structural energy harvesting and energy storage devices, functional organic and inorganic inks, and additive manufacturing/printing processes for sensors, interconnects, capacitors, and batteries.

Our research interests include several fundamental topics in this field. First, we work toward understanding the role of interfaces and morphology in these devices with a goal of tailoring device performance. Second, we employ a wide range of characterization tools to determine the fundamental physical phenomena in these materials and how they impact device operation. Third, we are interested in developing and improving processes that allow for conformal, thin-film deposition of solid state devices across a spectrum of length scales, form factors, and substrates. In all three of these areas we use a variety of analytical techniques including x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, atomic force microscopy, electron microscopy, time-of-flight mobility, and photoinduced absorption among other techniques. In addition to experimental investigation, we are also interested in applying computational and modeling methods to accelerate developmental efforts. These ICMSE approaches are expected to be particularly fruitful in predicting materials properties and behavior at interfaces.

SF.25.13.B7100: Hierarchical Reinforced Polymer Composites 

Baur, J.

(937) 255-9324

We are interested in understanding and manipulating the interfaces of structural fibers with nanomaterials to tailor the mechanical, electrical, thermal, and piezoresistive properties as a means to manipulate the interfacial properties of multifunctional polymer matrix composites. This effort involves coating or synthesis of high aspect carbon and inorganic nanotubes/nanowires upon structural fibers; characterization of their structures via TEM, SEM, and spectroscopy; and evaluation of electrical, mechanical, and thermal properties coupling properties at multiple scales.

SF.25.13.B7101: Additive Manufacturing of Polymer Composites 

Baur, J.

(937) 255-9324

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.B0111: Multiferroic Heterostructure Materials

Brown, G.J.

(937) 255-9854

This research focuses on the characterization of materials for enhancing the magneto-electric (ME) coupling in multiferroic heterostructures. High resistivity (low loss) ferrimagnets are used in a wide range of passive microwave components such as isolators, circulators, phase shifters, filters, resonators and miniature antennas operating at a wide range of frequencies (1-100 GHz). If paired with a piezoelectric material, changes in the electric field of the piezoelectric can be used to tune the magnetic properties of the ferrimagnet which opens up a whole host of tunable microwave passive components. Complex oxide heterostructures, such as oxide superlattices, which tailor the permeability and permittivity of the resulting layered material, and ferroelectric/ferromagnetic double layer materials for tunable devices are both of interest to this program. This project would primarily focus on the characterization of the ME coupling strength, the permittivity, the permeability and the ferromagnetic resonances in the fabricated materials. It could also include modeling of the materials to enhance these properties. We have specialized microwave characterization facilities such as field sweeping and frequency sweeping measurements of the ferromagnetic resonance, as well as the capability for growth of oxide thin films via pulsed laser deposition. In addition, there are many other facilities in-house that can also be utilized in the study of these materials, such as HRTEM, HRXRD, SEM, AFM, PFM, XPS, MFM SIMS, Auger spectroscopy, dielectric measurements and Hall Transport measurements.

SF.25.14.B0823: Modeling of Optical parametric Conversion 

Hopkins, F.

(937) 255-9890

Nonlinear optical crystals offer a practical means for converting the wavelength of light from solid-state lasers to the mid-infrared spectral region. AFRL/RX has been a leader in the development of many of these crystals including ZnGeP2, CdGeAs2, CdSiP2, and various quasi-phase matched crystals. A number of these crystals have been incorporated into various military and commercial products for lower average power applications. However, questions remain on the materials engineering required to scale such crystals for high average power handling. Modeling is needed to better understand the relationship of the crystal’s optical and thermal parameters to the output characteristics of a laser source (average power, cw versus pulsed, beam quality, efficiency, etc.).

Keywords:

Nonlinear Optics, Optical Parametric Conversion, Infrared Laser Sources

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. Calculations 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. Projects of interest are described below:

(1) Atomistic simulation is being used to investigate peptides that have been experimentally identified as “good” binders to inorganic and graphitic 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.

(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) Synthesis and characterization of hairy nanoparticles (HNP) is combined with coarse-grained MD simulations to characterize physical aging in neat HNP systems with the goal of establishing structure-property relationships to obtain maximum toughening of HNPs as a function of polymer (hair) structure, core composition (inorganics vs. polymeric), molecular weight distribution and graft density.

(4) Simulations have been and continue to be conducted to better understand the morphology and electrochemical properties of as well as to identify proper process parameters for the synthesis of organic photovoltaics (OPVs). MD simulations can be utilized to generate structures representative of the electron-blocking and active layers as well as the interface(s) between these layers, while electrochemical characteristics of these structures can be predicted using NEGF (non-equilibrium Green’s function) methods. At the intersection between computational evaluation and experimental validation, such methods are to be used to analyze process conditions for reducing the required experiments.

 

Keywords:

Nanoparticle; Bio-inspired; Bio-panning; Bio-mineralization; Force field; Coarse-Grain; Ab initio; Molecular dynamics; Density functional theory; Mechanical properties of polymer-composites; OPV, NEGF 

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 integrated within a stretchable matrix to enable new paradigms in flexible and stretchable electronics. The major hurdles to implementing these GaLMA materials are two-fold, specifically the spontaneously forming oxide skin on the liquid alloy and 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 damage prediction tools are crucial for damage tolerant multifunctional composites. Major failures in composites are associated with the huge difference in thermal expansion coefficient between the filler and the polymer matrix, issue with the interface / interphase, and poor reinforcement. Overcoming these challenges requires a careful design and a multidisciplinary approach combining synthesis, processing, characterization (across scales), and multi-scale modeling. We are interested in understanding the failure mode at the nano to the higher scale, and the underlying processing-structure-property relationship by combining both experimental and computational approaches. Key interests include elucidating the fundamental principles of the underlying fracture mechanism based on bonding-chemistry and shape / size / distribution of the nanofillers; investigating corresponding electrical and optical properties; establishing techniques to predict failure using molecular, meso-scale and continuum mechanics modeling. Techniques include bulk and surface spectroscopy, nanoscale chemical / physical / mechanical mapping, atomic force microscopy, electron microscopy, in-situ testing, digital image correlation, and multi-scale modeling.

Keywords: Nanostructure, Polymer, Nanocomposite, Composite, Chemical Imaging, Spectroscopy, Microscopy, Fracture, Mechanical Properties, Digital Image Correlation, Multiscale Modeling

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

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 and 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, 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:

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: Wide Band Gap Semiconductors for High Power RF Electronics in Extreme Environment

Ganguli, Sabyasachi

(937) 255-1139

An overarching theme for this research is the development of on high power RF electronics for extreme environments like hypersonic, munition, etc. We are primarily interested on ultra-wide band gap semiconductors like GaN, SiC, AlN, IGZO. Specific research would look into synthesis, device processing and device performance characterization of these wide band gap semiconductors. Material characterization methods like SEM and TEM (material microstructure and morphology), 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 background in various semiconductors and their electrical and thermal characterization techniques and in simple device processing techniques is desirable. This research program will address to Air Force needs for the next generation extreme environment survivable high power RF electronics.

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