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DOE OSTI2020

Pressure Effects on the Electronic and Optical Properties in Low-Dimensional Metal Halide Perovskites

Metal halide perovskites have shown enormous potential in perovskite solar cells and light-emitting diodes and made unprecedented progress in the past decade. Additionally, pressure engineering as an effective technique can systematically modify the electronic structures and physical properties of functional materials. Low-dimensional metal halide perovskites (0D, 1D, and 2D) with a variety of compositions have soft lattices that allow pressure to drastically modulate their structures and properties. High-pressure investigations have obtained a comprehensive understanding of their structure–property relationships. Simultaneously, discoveries of novel pressure-driven properties, such as metallization and partially retained band gap narrowing have contributed significantly to the further development of such materials. In this work, we mainly highlight the effect of pressure on the properties and structures of low-dimensional metal halide perovskites, which is essential for designing new perovskite materials and advancing applications.

36 MATERIALS SCIENCE↗

NASA NTRS2002

Hoof Comfort for Horses

Aquila Equine Enhancement Products, Inc., of Woburn, Massachusetts, developed magnetic hoof protector pads, called "Power Pads," which support and cushion the impact on a horse's hooves and legs to provide comfort and protection against injuries. The pads were tested by Marshall Space Flight Center's Materials and Processing Laboratory for strength and durability. Putting the pads on a horse does not interfere with its natural movement or flexibility and can be compared to a person changing into athletic shoes for a sporting event. The pads are cut to the appropriate size, and then mounted onto a horse's hooves using conventional shoeing methods. Once attached, the pads protect the hard and soft parts of the hoof by cushioning blows against the hard ground. The design also protects the vulnerable "heel" of the hoof. They are a cost-effective way to protect a horse's hooves since they can be reused.

Source record↗

NASA NTRS2001

Thermal Performance of Biological Substance Systems in Vitro Under Static and Dynamic Conditions at the Cryogenic Test Laboratory, NASA Kennedy Space Center, USA

A unique research program, including a comprehensive study of thermal performance at cryogenic vacuum insulation systems, was performed at the NASA Kennedy Space Center. The main goal was to develop a new soft vacuum system (from 1 torr to 10 torr) that provides an intermediate level of performance (k-value below 4.8 mW/m-K). Liquid nitrogen boil-off methods were used to test conventional materials, novel materials, and certain combinations. The test articles included combinations of aluminum foil, fiberglass paper, polyester fabric, silica aerogel composite blanket, fumed silica, silica aerogel powder, and syntactic foam. A new LCI system was developed at the Cryogenics Test Laboratory. This system performs exceptionally well at soft vacuum levels and nearly as good as an MLI at high vacuum levels. Apparent thermal conductivities for the LCI range from 2 mW/m-K at soft vacuum to 0.1 mW/m-K at high vacuum. Several cryostats were designed, constructed, and calibrated by the Cryogenics Test Laboratory at KSC NASA as part of this research program. The cryostat test apparatus is a liquid nitrogen boil-off calorimeter system for direct measurement of the apparent thermal conductivity at a fixed vacuum level between 5 x 10(exp -5) and 760 torr. The apparatus is also used for transient measurements of temperature profiles. The development of efficient, robust cryogenic insulation systems has been a targeted area of research for a number of years. Improved methods of characterization, testing, and evaluation of complex biological substance systems for cryosurgery and cryobiology are the focus of this paper.

Augustynowicz, S. D.↗

NASA NTRS2018

Development of an Inflatable Airlock for Deep Space Exploration

An airlock is a required component of a crewed spacecraft to allow for maintenance, repair and exploration outside of a habitable vehicle. Airlock designs in use today are rigid pressure vessels with complex hatches and seals. Inflatable structures technology utilizes high strength fabric materials and internal pressure to create a stiffened pressure vessel that can replace traditional rigid primary structure in a habitable spacecraft. The flexibility of fabric structures allows them to be compactly stowed for launch and expanded in space. Recent developments towards the design of an inflatable airlock structure show feasibility and a significant launch volume savings over a traditional metallic design. This paper provides a detailed summary of historical and current work in inflatable airlock development and provides guidance for the design of a soft goods airlock system. Accommodations for withstanding crew-induced loads, provisions for human interfaces, the design and development of an internal substructure to provide translation aids and restraints, the thermal considerations of a fabric shell, micrometeoroid protection in deep space, and packaging and deployment of an inflatable airlock are all discussed.

Deep Space Exploration↗

DOE OSTI2022

Deconvoluting sources of failure in lithium metal batteries containing NMC and PEO-based electrolytes

Solid-state lithium metal batteries (SSLMBs) containing polyethylene oxide (PEO)-derived polymer electrolytes and high-voltage (> 4 V vs. Li/Li + ) cathode materials suffer from three sources of failure: (1) instability between the polymer electrolyte and cathode at high voltage, (2) instability of the polymer electrolyte with Li metal, and (3) poorly-designed cathodes. In this study, these three sources of failure are deconvoluted by studying Ni-rich LiNi x Mn y Co 1-x-y O 2 (NMC, x ≥ 0.6) cathodes and a gel polymer electrolyte (GPE) derived from PEO. Initial cycling data reveals that rapid capacity fade occurs regardless of whether soft short circuits form due to Li dendrites. Cyclic voltammetry scans on cells featuring a Li metal electrode, GPE, and a NMC811 electrode free of additives suggest that there are no runaway reactions between the GPE and NMC811 up to 4.5 V vs. Li/Li + . Cathode/cathode symmetric cell cycling demonstrates that Li metal reactivity is a prime source of failure, though a poorly-designed cathode leads to subpar performance. A cathode with single-crystal NMC particles was demonstrated to achieve better initial capacity and longer cycle life, indicating room for improvement in SSLMB cathode design. Therefore, the sources of failure as enumerated may be ranked as follows from most to least concerning: 2 > 3 > 1.

25 ENERGY STORAGE↗

DOE OSTI2022

Synchrotron-based techniques for characterizing STCH water-splitting materials

Understanding the role of oxygen vacancy–induced atomic and electronic structural changes to complex metal oxides during water-splitting processes is paramount to advancing the field of solar thermochemical hydrogen production (STCH). The formulation and confirmation of a mechanism for these types of chemical reactions necessitate a multifaceted experimental approach, featuring advanced structural characterization methods. Synchrotron X-ray techniques are essential to the rapidly advancing field of STCH in part due to properties such as high brilliance, high coherence, and variable energy that provide sensitivity, resolution, and rapid data acquisition times required for the characterization of complex metal oxides during water-splitting cycles. X-ray diffraction (XRD) is commonly used for determining the structures and phase purity of new materials synthesized by solid-state techniques and monitoring the structural integrity of oxides during water-splitting processes (e.g., oxygen vacancy–induced lattice expansion). X-ray absorption spectroscopy (XAS) is an element-specific technique and is sensitive to local atomic and electronic changes encountered around metal coordination centers during redox. While in operando measurements are desirable, the experimental conditions required for such measurements (high temperatures, controlled oxygen partial pressures, and H 2 O) practically necessitate in situ measurements that do not meet all operating conditions or ex situ measurements. Here, we highlight the application of synchrotron X-ray scattering and spectroscopic techniques using both in situ and ex situ measurements, emphasizing the advantages and limitations of each method as they relate to water-splitting processes. The best practices are discussed for preparing quenched states of reduction and performing synchrotron measurements, which focus on XRD and XAS at soft (e.g., oxygen K-edge, transition metal L-edges, and lanthanide M-edges) and hard (e.g., transition metal K-edges and lanthanide L-edges) X-ray energies. The X-ray absorption spectra of these complex oxides are a convolution of multiple contributions with accurate interpretation being contingent on computational methods. The state-of-the-art methods are discussed that enable peak positions and intensities to be related to material electronic and structural properties. Through careful experimental design, these studies can elucidate complex structure–property relationships as they pertain to nonstoichiometric water splitting. A survey of modern approaches for the evaluation of water-splitting materials at synchrotron sources under various experimental conditions is provided, and available software for data analysis is discussed.

08 HYDROGEN↗

NASA NTRS2016

Soft-Robotic Rover with Electrodynamic Power Scavenging: NIAC Final Report - Phase 1

The purpose of studying the capabilities of Electrodynamic Tethers (EDT) and Soft Robotics is to ascertain the feasibility of using cross-cutting EDT and soft robotics technologies to achieve future NASA mission objectives with mass and power budgets orders of magnitude lower than conventional spacecraft. In this context, the Phase I study focuses on three technological elements: the design of a soft-robotic rover that can operate in extraterrestrial oceans, demonstrating feasibility of electrodynamic tethers for power scavenging in the Europa environment, and utilizing electrolysis to power biomimetic propulsion.The Phase I results show that a soft robotic, underwater rover has many advantages over a traditional view of autonomous underwater vehicles. Many of these advantages stem from its ability to collapse or expand the body, which carries two key benefits: (i) cost savings in transport and (ii) buoyancy control. Furthermore, this rover's material offers properties that enable it to survive most oceanic conditions, withstand a likely radiation environment, and retard ice formation. The use of these soft robots under water is very attractive because buoyancy enables very large robots without the need for skeletal structures that limit their shape-changing ability. The prime limitation of soft robots for underwater exploration is their nascent state of development, an issue that this study has begun to address and that we hope to continue in Phase II. The theoretical calculations and experimental investigation on electrodynamic tethers discussed in this report show that their use in saltwater environments is feasible. However, magneto hydrodynamic effects require attention, which will be a priority in Phase II. A possible approach involves magnetic shielding of a portion of the EDT array to generate significant current from imposed alternating magnetic fields. The Phase I experiments show that this approach may enable enough power to be generated for a soft robotic rover of the scale contemplated here. This power is in the range of 1mW to 1W and determines the time required to collect and transmit science data.

Soft Robotics↗

NASA NTRS1993

Impact damage resistance of composite fuselage structure, part 2

The strength of laminated composite materials may be significantly reduced by foreign object impact induced damage. An understanding of the damage state is required in order to predict the behavior of structure under operational loads or to optimize the structural configuration. Types of damage typically induced in laminated materials during an impact event include transverse matrix cracking, delamination, and/or fiber breakage. The details of the damage state and its influence on structural behavior depend on the location of the impact. Damage in the skin may act as a soft inclusion or affect panel stability, while damage occurring over a stiffener may include debonding of the stiffener flange from the skin. An experiment to characterize impact damage resistance of fuselage structure as a function of structural configuration and impact threat was performed. A wide range of variables associated with aircraft fuselage structure such as material type and stiffener geometry (termed, intrinsic variables) and variables related to the operating environment such as impactor mass and diameter (termed, extrinsic variables) were studied using a statistically based design-of-experiments technique. The experimental design resulted in thirty-two different 3-stiffener panels. These configured panels were impacted in various locations with a number of impactor configurations, weights, and energies. The results obtained from an examination of impacts in the skin midbay and hail simulation impacts are documented. The current discussion is a continuation of that work with a focus on nondiscrete characterization of the midbay hail simulation impacts and discrete characterization of impact damage for impacts over the stiffener.

Dost, Ernest F.↗

NASA NTRS2016

Testing of Space Suit Materials for Mars

Human missions to Mars may require radical changes in our approach to EVA suit design. A major challenge is the balance of building a suit robust enough to complete 50 EVAs in the dirt under intense UV exposure without losing mechanical strength or compromising its mobility. We conducted ground testing on both current and new space suit materials to determine performance degradation after exposure to 2500 hours of Mars mission equivalent UV. This testing will help mature the material technologies and provide performance data that can be used by not only the space suit development teams but for all Mars inflatable and soft goods derived structures from airlocks to habitats.

Larson, Kristine↗

DOE OSTI2021

Additive manufacturing and applications of nanomaterial-based sensors

Nanoscale materials possess distinct physical and chemical attributes including size-dependent properties, quantum confinement, high surface-to-volume ratio, and superior catalytic activity. These unique qualities enable sensors with high sensitivity, robustness, and fast time response. As the emergence of the Internet of Things (IoT) demands increased production of sensors, it also provides an impetus for concentrated nanomaterial-based sensor research. Meanwhile, additive manufacturing (AM) of nanomaterial-based sensors is critical to bridge the gap between one-off, lab-scale fabrication and cost-effective, industrial-scale production with high reproducibility. By applying the design flexibility and cost savings of AM techniques, a new generation of nanomaterial-based sensing platforms can be integrated with IoT devices in the consumer space. Furthermore, emergent research in human-machine interfaces, food safety, and point-of-care diagnostics will be expedited by the development of sensors that can be printed with irregular form factors. In this Review, the relative strengths and weaknesses of printed sensor systems based on zero-, one-, and two-dimensional nanomaterials are discussed. In addition, sensors enabled by printable soft nanomaterials, heterostructures, and nanocomposites are surveyed due to their synergistic advantages for wearable healthcare monitoring and soft robotics. Lastly, a roadmap for the next decade of research on this topic is provided.

36 MATERIALS SCIENCE↗

DOE OSTI2024

X-ray Irradiance Distribution for an Interferometer with a Curved Biprism Array

The development of interferometry-based X-ray phase contrast imaging systems that provide highly resolved X-rays with spatially-modulated intensity is enabling the full potential of X-ray optics to image phase, attenuation, and small angle scatter properties of soft tissue. In this work we present analytical formulations of a new hardware concept for X-ray phase contrast imaging wherein the phase grating is replaced with an array of Fresnel biprisms. We derive expressions for the irradiance distribution pattern of a biprism interferometer composed of a curved biprism array with multiple biprisms and multiple point sources. These expressions are used to plot fringe patterns for X-ray design parameters, including 1) size, number, and period of X-ray point sources; 2) biprism parameters of material composition, angle, number, and period; and 3) biprism array to X-ray source and detector distances. Analytical results show that the biprism interferometer provides a longitudinally-nonperiodic pattern of spatially modulated intensity different from the Talbot longitudinally-periodic pattern common in grating interferometry. The curvature of the biprism array brings a sharper longitudinal fringe pattern. Experiments are being performed to verify the analytical calculations for a biprism plastic material of SU-8 using a synchrotron source. X-ray biprism material has widely varied indexes of refraction relative to wavelength and thus the separation of the virtual sources and resulting interference fringe period also varies with X-ray wavelength. Our aim is to develop biprism interferometry imaging systems with excellent polychromatic performance that produce high-contrast fringes with spatially incoherent X-ray illumination. Biprism interferometry will potentially provide higher fringe visibility with better image quality to that of diffraction grating interferometry.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2021

Design of a Single Layer Metamaterial for Pressure Offloading of Transtibial Amputees

While using a prosthesis, transtibial amputees may experience pain and discomfort brought on by large pressure gradients at the interface between the residual limb and prosthetic socket. Current prosthetic interface solutions attempt to alleviate these pressure gradients by using soft homogenous liners to reduce and distribute pressures. This research investigates an additively manufactured metamaterial inlay with a tailored mechanical response to reduce peak pressure gradients around the limb. The inlay uses a hyperelastic behaving metamaterial (US10244818) comprised of triangular pattern unit cells which can be 3D printed with walls of various thicknesses controlled by draft angles. The hyperelastic material properties are modeled using a Yeoh 3rd order model. The 3rd order coefficients can be adjusted and optimized, which corresponds to a change in the unit cell wall thickness to create an inlay that can meet the unique offloading needs of an amputee. Finite element analysis simulations evaluated the pressure gradient reduction from: 1) a common homogenous silicone liner, 2) a prosthetist's inlay prescription that utilizes three variations of the metamaterial, and 3) a metamaterial solution with optimized Yeoh 3rd order coefficients. When compared to a traditional homogenous silicone liner for two unique limb loading scenarios, the prosthetist prescribed inlay and the optimized material inlay can achieve equal or greater pressure gradient reduction capabilities. These results show the potential feasibility of implementing this metamaterial as a method of personalized medicine for transtibial amputees by creating a customizable interface solution to meet the unique performance needs of an individual patient.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2023

Highly Deformable Rigid Glassy Conjugated Polymeric Thin Films

Wearable devices benefit from the use of stretchable conjugated polymers (CPs). Traditionally, the design of stretchable CPs is based on the assumption that a low elastic modulus (E) is crucial for achieving high stretchability. However, this research, which analyzes the mechanical properties of 65 CP thin films, challenges this notion. It is discovered that softness alone does not determine stretchability; rather, it is the degree of entanglement that is critical. This means that rigid CPs can also exhibit high stretchability, contradicting conventional wisdom. To inverstigate further, the mechanical behavior, electrical properties, and deformation mechanism of two model CPs: a glassy poly(3-butylthiophene-2,5-diyl) (P3BT) with an E of 2.2 GPa and a viscoelastic poly(3-octylthiophene-2,5-diyl) (P3OT) with an E of 86 MPa, are studied. Ex situ transmission X-ray scattering and polarized UV–vis spectroscopy revealed that only the initial strain (i.e., <20%) exhibits different chain alignment mechanisms between two polymers, while both rigid and soft P3ATs showed similarly behavior at larger strains. In conclusion, by challenging the conventional design metric of low E for high stretchability and highlighting the importance of entanglement, it is hoped to broaden the range of CPs available for use in wearable devices.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Erratum to: Soft- and reactive landing of ions onto surfaces: concepts and applications

Soft- and reactive landing of mass-selected ions is gaining attention as a promising approach for the precisely-controlled preparation of materials on surfaces that are not amenable to deposition using conventional methods. A broad range of ionization sources and mass filters are available that make ion soft-landing a versatile tool for surface modification using beams of hyperthermal (<100?eV) ions. The ability to select the mass-to-charge ratio of the ion, its kinetic energy and charge state, along with precise control of the size, shape, and position of the ion beam on the deposition target distinguishes ion soft landing from other surface modification techniques. Soft- and reactive landing have been used to prepare interfaces for practical applications as well as precisely-defined model surfaces for fundamental investigations in chemistry, physics, and materials science. For instance, soft- and reactive landing have been applied to study the surface chemistry of ions isolated in the gas-phase, prepare arrays of proteins for high-throughput biological screening, produce novel carbon-based and polymer materials, enrich the secondary structure of peptides and the chirality of organic molecules, immobilize electrochemically-active proteins and organometallics on electrodes, create thin films of complex molecules, and immobilize catalytically active organometallics as well as ligated metal clusters. In addition, soft landing has enabled investigation of the size-dependent behavior of bare metal clusters in the critical subnanometer size regime where chemical and physical properties do not scale predictably with size. The morphology, aggregation, and immobilization of larger bare metal nanoparticles, which are directly relevant to the design of catalysts as well as improved memory and electronic devices, have also been studied using ion soft landing. This review article begins in section 1 with a brief introduction to the existing applications of ion soft- and reactive landing. Section 2 provides an overview of the ionization sources and mass filters that have been used to date for soft landing of mass-selected ions. A discussion of the competing processes that occur during ion deposition as well as the types of ions and surfaces that have been investigated follows in section 3. Section 4 discusses the physical phenomena that occur during and after ion soft landing, including retention and reduction of ionic charge along with factors that impact the efficiency of ion deposition. The influence of soft landing on the secondary structure and biological activity of complex ions is addressed in section 5. Lastly, an overview of the structure and mobility as well as the catalytic, optical, magnetic, and redox properties of bare ionic clusters and nanoparticles deposited onto surfaces is presented in section 6. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:439–479, 2016.

Johnson, Grant E.↗

NASA NTRS2018

Sample Return Systems for Extreme Environments (SaRSEE)

Sample return missions offer a greater science yield when compared to missions that only employ in situ experiments or remote sensing observations, since they allow the application of more complex technological and analytical methodologies in controlled terrestrial laboratories,that are both repeatable and can be independently verified. The successful return of extraterrestrial materials over the last four decades has contributed to our understanding of the solar system, but retrieval techniques have largely depended on the use of either soft-landing, or touch-and-go procedures that result in high V requirements, larger spacecraft mass ratios, and return yields typically limited to a few grams of surface materials that have experienced varying degrees of alteration from space weathering. Hard-landing methods using planetary penetrators offer an alternative for sample return that significantly reduce a mission's V and mass ratios,increase sample yields, and allow for the collection of subsurface materials, and lessons can be drawn from previous sample return missions. The following details progress in the design,development, and testing of penetrator/sampler technology capable of surviving subsonic and low, supersonic impact velocities (<700 m/s) that would enable the collection of geologic materials using tether technology to return the sample to a passing spacecraft. The testing of energy absorbing material for protecting the sample, design evolution and field testing of the penetrator, and dynamic modeling of tether behavior during sampling are discussed. It is shown through both modeling and field testing that penetrators at speeds between 300-600 m/s (~Mach 1-2) can penetrator into the ground to depths of 1-2 m with overall structural integrity attained.The first flight tests demonstrated the potential for survivability at these speeds. The second flight series demonstrated core sample collection with partial ejection of the sample return canister. The 3rd flight series demonstrated self-ejection of the sample return system fully intact and with the core retaining the full stratigraphy of the rock bed. The tether analysis shows that the forces on the tether during release and return of the sample to the main spacecraft are all at levels that can easily be handled by existing tether materials. The mass analysis of the requirements indicates that sample return form the asteroids could be handled with Discovery or New Frontier range of missions dependent on the number of samples to be returned to the Earth.

Winglee, R. M.↗

NASA NTRS2009

Design and Testing of Braided Composite Fan Case Materials and Components

Triaxial braid composite materials are beginning to be used in fan cases for commercial gas turbine engines. The primary benefit for the use of composite materials is reduced weight and the associated reduction in fuel consumption. However, there are also cost benefits in some applications. This paper presents a description of the braided composite materials and discusses aspects of the braiding process that can be utilized for efficient fabrication of composite cases. The paper also presents an approach that was developed for evaluating the braided composite materials and composite fan cases in a ballistic impact laboratory. Impact of composite panels with a soft projectile is used for materials evaluation. Impact of composite fan cases with fan blades or blade-like projectiles is used to evaluate containment capability. A post-impact structural load test is used to evaluate the capability of the impacted fan case to survive dynamic loads during engine spool down. Validation of these new test methods is demonstrated by comparison with results of engine blade-out tests.

Roberts, Gary D.↗

NASA NTRS2009

Design and Testing of Braided Composite Fan Case Materials and Components

Roberts, Gary D.↗

DOE OSTI2020

Effect of Molecular Weight and Layer Thickness on Dielectric Breakdown Strength of Neat and Homopolymer Swollen Lamellar Block Copolymer Films

Designing next-generation lightweight pulsed power devices hinges on understanding the factors influencing the energy storage performance of dielectric materials. Polymer dielectric films have a quadratic dependence of energy storage on the voltage breakdown strength and strategies to enhance the breakdown strength are expected to yield a path toward high energy storage densities. Highly stratified lamellar block copolymer (L-BCP) films of model polystyrene-b-polymethylmethacrylate (PS-b-PMMA) exhibited as much as ~50% enhancement in breakdown voltage (E BD ), (225 % increase in stored energy density, U~ E BD 2 ), compared to unordered as-cast L-BCP films. Such an energy density using amorphous polymer is on par with industry-standard semi-crystalline biaxially oriented polypropylene (BOPP), and as such a notable development in the field. This work develops a deeper understanding of the molecular mechanisms of E BD enhancement in L-BCP films, due to combination of interface formation and spatial isolation of the chain ends into segregated zones. We further confirm the role of chain ends in the breakdown process blending a low M n L-BCP with matched M n homopolymers to attain same layer spacing as neat L-BCP of higher M n . E BD shows a significant decrease at low homopolymer fractions due to increased net chain end density within swollen ordered L-BCP domains in wet-brush regime, followed by increased E BD due to layer thickness increase via segregated “interphase layer” formation by excess homopolymers. Notably, E BD of homopolymer swollen L-BCPs is always lower than neat L-BCP of the same domain spacing, due to overall adverse chain ends contribution from homopolymers. These findings provide important selection rules for L-BCPs for designing next-generation flexible electronics with high energy density solid-state BCP film capacitors.

36 MATERIALS SCIENCE↗