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DOE OSTI2022

Synthetic Nuances to Maximize n-Type Organic Electrochemical Transistor and Thermoelectric Performance in Fused Lactam Polymers

A series of fully fused n-type mixed conduction lactam polymers p(g 7 NC n N), systematically increasing the alkyl side chain content, are synthesized via an inexpensive, nontoxic, precious-metal-free aldol polycondensation. Employing these polymers as channel materials in organic electrochemical transistors (OECTs) affords state-of-the-art n-type performance with p(g 7 NC 10 N) recording an OECT electron mobility of 1.20 x 10 -2 cm 2 V -1 s -1 and a μC* figure of merit of 1.83 F cm -1 V -1 s -1. In parallel to high OECT performance, upon solution doping with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI), the highest thermoelectric performance is observed for p(g 7 NC 4 N), with a maximum electrical conductivity of 7.67 S cm -1 and a power factor of 10.4 μWm -1 K -2 . These results are among the highest reported for n-type polymers. Importantly, while this series of fused polylactam organic mixed ionic-electronic conductors (OMIECs) highlights that synthetic molecular design strategies to bolster OECT performance can be translated to also achieve high organic thermoelectric (OTE) performance, a nuanced synthetic approach must be used to optimize performance. Herein, we outline the performance metrics and provide new insights into the molecular design guidelines for the next generation of high-performance n-type materials for mixed conduction applications, presenting for the first time the results of a single polymer series within both OECT and OTE applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Defects and Defect Engineering of Two-Dimensional Transition Metal Dichalcogenide (2D TMDC) Materials

As layered materials, transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) materials. Interestingly, the characteristics of these materials are transformed from bulk to monolayer. The atomically thin TMDC materials can be a good alternative to group III–V and graphene because of their emerging tunable electrical, optical, and magnetic properties. Although 2D monolayers from natural TMDC materials exhibit the purest form, they have intrinsic defects that limit their application. However, the synthesis of TMDC materials using the existing fabrication tools and techniques is also not immune to defects. Additionally, it is difficult to synthesize wafer-scale TMDC materials for a multitude of factors influencing grain growth mechanisms. While defect engineering techniques may reduce the percentage of defects, the available methods have constraints for healing defects at the desired level. Thus, this holistic review of 2D TMDC materials encapsulates the fundamental structure of TMDC materials, including different types of defects, named zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D). Moreover, the existing defect engineering methods that relate to both formation of and reduction in defects have been discussed. Finally, an attempt has been made to correlate the impact of defects and the properties of these TMDC materials.

2D materials↗

NASA NTRS2012

Sealing Materials for Use in Vacuum at High Temperatures

Sealing materials that can be applied and left in place in vacuum over a wide range of temperatures (especially temperatures of a few thousand degrees Celsius) have been conceived and investigated for potential utility in repairing thermal-protection tiles on the space shuttles in orbit before returning to Earth. These materials are also adaptable to numerous terrestrial applications that involve vacuum processing and/or repair of structures that must withstand high temperatures. These materials can be formulated to have mechanical handling characteristics ranging from almost freely flowing liquid-like consistency through paste-like consistency to stiff puttylike consistency, and to retain these characteristics in vacuum until heated to high curing temperatures. A sealing material of this type can be formulated to be used in any of several different ways for example, to be impregnated into a high-temperature-fabric patch, impregnated into a high-temperature-fabric gasket for sealing a patch, applied under a patch, or applied alone in the manner of putty or wallboard compound. The sealing material must be formulated to be compatible with, and adhere to, the structural material(s) to be repaired. In general, the material consists of a vacuum-compatible liquid containing one or more dissolved compound(s) and/or mixed with suspended solid particles. Depending on the intended application, the liquid can be chosen to be of a compound that can remain in place in vacuum for a time long enough to be useful, and/or to evaporate or decompose in a controlled way to leave a useful solid residue behind. The evaporation rate is determined by proper choice of vapor pressure, application of heat, and/or application of ultraviolet light or other optical radiation. The liquid chosen for the original space shuttle application is a commercial silicone vacuum-pump oil.

Pettit, Donald R.↗

NASA NTRS2001

Microgravity Materials Science Conference 2000

This is Volume 1 of 3 of the 2000 Microgravity Material Science Conference that was held June 6-8 at the Von Braun Center, Huntsville, Alabama. It was organized by the Microgravity Materials Science Discipline Working Group, sponsored by the Microgravity Research Division (MRD) at NASA Headquarters, and hosted by NASA Marshall Space Flight Center and the Alliance for Microgravity Materials Science and Applications (AMMSA). It was the fourth NASA conference of this type in the microgravity materials science discipline. The microgravity science program sponsored approx. 200 investigators, all of whom made oral or poster presentations at this conference. In addition, posters and exhibits covering NASA microgravity facilities, advanced technology development projects sponsored by the NASA Microgravity Research Division at NASA Headquarters, and commercial interests were exhibited. The purpose of the conference was to inform the materials science community of research opportunities in reduced gravity and to highlight the Spring 2001 release of the NASA Research Announcement (NRA) to solicit proposals for future investigations. It also served to review the current research and activities in materials science, to discuss the envisioned long-term goals. and to highlight new crosscutting research areas of particular interest to MRD. The conference was aimed at materials science researchers from academia, industry, and government. A workshop on in situ resource utilization (ISRU) was held in conjunction with the conference with the goal of evaluating and prioritizing processing issues in Lunar and Martian type environments. The workshop participation included invited speakers and investigators currently funded in the material science program under the Human Exploration and Development of Space (HEDS) initiative. The conference featured a plenary session every day with an invited speaker that was followed by three parallel breakout sessions in subdisciplines. Attendance was close to 350 people. Posters were available for viewing during the conference and a dedicated poster session was held on the second day. Nanotechnology radiation shielding materials, Space Station science opportunities, biomaterials research, and outreach and educational aspects of the program were featured in the plenary talks. This volume, the first to be released on CD-ROM for materials science, is comprised of the research reports submitted by the Principal Investigators at the conference.

Ramachandran, Narayanan↗

NASA NTRS2001

Microgravity Materials Science Conference 2000

This is Volume 2 of 3 of the 2000 Microgravity Materials Science Conference that was held June 6-8 at the Von Braun Center, Huntsville, Alabama. It was organized by the Microgravity Materials Science Discipline Working Group, sponsored by the Microgravity Research Division (MRD) at NASA Headquarters, and hosted by NASA Marshall Space Flight Center and the Alliance for Microgravity Materials Science and Applications (AMMSA). It was the fourth NASA conference of this type in the Microgravity materials science discipline. The microgravity science program sponsored approx. 200 investigators, all of whom made oral or poster presentations at this conference- In addition, posters and exhibits covering NASA microgravity facilities, advanced technology development projects sponsored by the NASA Microgravity Research Division at NASA Headquarters, and commercial interests were exhibited. The purpose of the conference %%,its to inform the materials science community of research opportunities in reduced gravity and to highlight the Spring 2001 release of the NASA Research Announcement (NRA) to solicit proposals for future investigations. It also served to review the current research and activities in material,, science, to discuss the envisioned long-term goals. and to highlight new crosscutting research areas of particular interest to MRD. The conference was aimed at materials science researchers from academia, industry, and government. A workshop on in situ resource utilization (ISRU) was held in conjunction with the conference with the goal of evaluating and prioritizing processing issues in Lunar and Martian type environments. The workshop participation included invited speakers and investigators currently funded in the material science program under the Human Exploration and Development of Space (HEDS) initiative. The conference featured a plenary session every day with an invited speaker that was followed by three parallel breakout sessions in subdisciplines. Attendance was close to 350 people, Posters were available for viewing during the conference and a dedicated poster session was held on the second day. Nanotechnology, radiation shielding materials, Space Station science opportunities, biomaterials research, and outreach and educational aspects of the program were featured in the plenary talks. This volume, the first to be released on CD-ROM for materials science, is comprised of the research reports submitted by the Principal Investigators at the conference.

Ramachandran, Narayanan↗

NASA NTRS2001

Microgravity Materials Science Conference 2000

This is Volume 3 of 3 of the 2000 Microgravity Materials Science Conference that was held June 6-8 at the Von Braun Center, Huntsville, Alabama. It was organized by the Microgravity Materials Science Discipline Working Group, sponsored by the Microgravity Research Division (MRD) at NASA Headquarters, and hosted by NASA Marshall Space Flight Center and the Alliance for Microgravity Materials Science and Applications (AMMSA). It was the fourth NASA conference of this type in the Microgravity materials science discipline. The microgravity science program sponsored ~200 investigators, all of whom made oral or poster presentations at this conference- In addition, posters and exhibits covering NASA microgravity facilities, advanced technology development projects sponsored by the NASA Microgravity Research Division at NASA Headquarters, and commercial interests were exhibited. The purpose of the conference was to inform the materials science community of research opportunities in reduced gravity and to highlight the Spring 2001 release of the NASA Research Announcement (NRA) to solicit proposals for future investigations. It also served to review the current research and activities in material,, science, to discuss the envisioned long-term goals. and to highlight new crosscutting research areas of particular interest to MRD. The conference was aimed at materials science researchers from academia, industry, and government. A workshop on in situ resource utilization (ISRU) was held in conjunction with the conference with the goal of evaluating and prioritizing processing issues in Lunar and Martian type environments. The workshop participation included invited speakers and investigators currently funded in the material science program under the Human Exploration and Development of Space (HEDS) initiative. The conference featured a plenary session every day with an invited speaker that was followed by three parallel breakout sessions in subdisciplines. Attendance was close to 350 people, Posters were available for viewing during the conference and a dedicated poster session was held on the second day. Nanotechnology, radiation shielding materials, Space Station science opportunities, biomaterials research, and outreach and educational aspects of the program were featured in the plenary talks. This volume, the first to be released on CD-ROM for materials science, is comprised of the research reports submitted by the Principal Investigators at the conference.

Ramachandran, Narayanan↗

DOE OSTI2014

Role of phonon scattering by elastic strain field in thermoelectric Sr{sub 1−x}Y{sub x}TiO{sub 3−δ}

Perovskite-type SrTiO{sub 3−δ} ceramics are multifunctional materials with significant potential as n-type thermoelectric (TE) materials. The electronic and thermal transport properties of spark plasma sintered polycrystalline Sr{sub 1−x}Y{sub x}TiO{sub 3−δ} (x = 0.05, 0.075, 0.1) ceramics are systematically investigated from (15–800) K. The Sr{sub 0.9}Y{sub 0.1}TiO{sub 3−δ} simultaneously exhibits a large Seebeck coefficient, α > −80 μV/K and moderately high electrical resistivity, ρ ∼ 0.8 mΩ-cm at a carrier concentration of ∼10{sup 21} cm{sup −3} at 300 K resulting in a high TE power factor defined herein as (α{sup 2}σT) ∼ 0.84 W/m-K at 760 K. Despite the similar atomic masses of Sr (87.6 g/mol) and Y (88.9 g/mol), the lattice thermal conductivity (κ{sub L}) of Sr{sub 1−x}Y{sub x}TiO{sub 3−δ} is significantly reduced with increased Y-doping, owing to the smaller ionic radii of Y{sup 3+} (∼1.23 Å, coordination number 12) compared to Sr{sup 2+} (∼1.44 Å, coordination number 12) ions. In order to understand the thermal conductivity reduction mechanism, the κ{sub L} in the Sr{sub 1−x}Y{sub x}TiO{sub 3−δ} series are phenomenologically modeled with a modified Callaway's equation from 30–600 K. Phonon scattering by elastic strain field due to ionic radii mismatch is found to be the prominent scattering mechanism in reducing κ{sub L} of these materials. In addition, the effect of Y-doping on the elastic moduli of Sr{sub 1−x}Y{sub x}TiO{sub 3−δ} (x = 0, 0.1) is investigated using resonant ultrasound spectroscopy, which exhibits an anomaly in x = 0.1 in the temperature range 300–600 K. As a result, the phonon mean free path is found to be further reduced in the Sr{sub 0.9}Y{sub 0.1}TiO{sub 3−δ} compared to that of SrTiO{sub 3−δ}, resulting in a considerably low thermal conductivity κ ∼ 2.7 W/m-K at 760 K. Finally, we report a thermoelectric figure of merit (ZT) ∼ 0.3 at 760 K in the Sr{sub 0.9}Y{sub 0.1}TiO{sub 3−δ}, the highest ZT value reported in the Y-doped SrTiO{sub 3} ceramics thus far.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2020

Intermediate-Term Thermal Aging Effect Evaluation for Grade 92 and 316L at The LWR Relevant Temperature

Life extension of the existing nuclear reactors imposes accumulated damages, such as higher fluences and longer period of corrosion, to structural materials, which would result in significant challenges to the traditional reactor materials such as type 304 and 316 stainless steels. Advanced alloys with superior radiation resistance will increase safety margins, design flexibility, and economics for not only the life extension of the existing fleet but also new builds with advanced reactor designs. The Electric Power Research Institute (EPRI) teamed up with Department of Energy (DOE) on the Advanced Radiation Resistant Materials (ARRM) program, aiming to develop and test degradation resistant alloys from current commercial alloy specifications by 2021 to a new advanced alloy with superior degradation resistance in light water reactor (LWR)-relevant environments by 2024. Based on a comprehensive microstructure and property screening performed in Phase-1 of the ARRM program, a total of five alloys, together with 316L and X-750 as references, were down-selected for Phase-2 neutron irradiation studies. Because thermal aging could exert a synergistic effect on neutron irradiation due to the low neutron damage rate on the order of 10 –7 displacements per atom per second (dpa/s), Grade 92 (one of the five down-selected alloys) and two heats of 316L were selected in this task to study the effect of aging at 350°C for 12.5–12.7 kh on microstructure and mechanical properties. The aging time is approximately corresponding to 5 dpa neutron irradiation, which can be served as a reference for the 5-dpa-irradiated samples of the alloys to help understand the independent neutron damage influence on microstructure and mechanical properties. Optical microscopy and scanning electron microscopy were used for microstructural characterization. Hardness, tensile, Charpy impact toughness, and fracture toughness in the ductile regime of the aged samples were examined. The aging of Grade 92 led to the formation of many Laves phase in sizes of ~100–200 nm and resulted in some reduction in hardness and yield/ultimate tensile strength with some increases in uniform and total plastic elongations, which may have helped the enhancement of Charpy impact toughness, e.g., ~4 J increase in upper-shelf energy and 20.5°C reduction in ductile-brittle transition temperature compared with the unaged condition. The fracture toughness of the aged Grade 92 showed decent toughness of ~303 MPa√m (K Jq ) with ~87 tearing modulus at 22°C, which reduced to ~241 MPa√m (~20% reduction) with ~75 tearing modulus at 300°C. The two heats of 316L are differentiated by their amounts of δ-ferrite, i.e., ~1 vol% in heat T1103 and ~4 vol% in heat N5B8. The two heats of 316L were subjected to 15% cold work (CW) as this condition is often used in nuclear reactors to help trapping radiation-induced defects and thus postpone the steady state swelling stage. The aging did not result in any noticeable microstructure changes, except for possible segregations at grain boundaries that need to be further investigated. The aging resulted in slight reduction in hardness of 316L-T1103 and slight increase in hardness of 316L-N5B8, which is consistent with their tensile testing results. The 15%CW might have introduced some inhomogeneity, resulting in large standard deviations in hardness, which were reduced after the aging. The aged 316L followed the same trend as the unaged condition for the strength and elongation results from the tensile testing. Minimum elongations appeared within ~300–600°C, above which the elongations seem to increase. Unlike the negligible or minor changes in microstructure, hardness and tensile results of the two heats of 316L, their fracture toughness showed noticeable difference. The aged 316L-T1103 showed good toughness of ~350 MPa√m with ~80 tearing modulus at 22°C, which reduced to ~271 MPa√m (~23% reduction) with ~83 tearing modulus at 300°C. In contrast, the aged 316L-N5B8 showed lower toughness of ~244 MPa√m with ~53 tearing modulus at 22°C, which reduced to ~180 MPa√m (~26% reduction) with ~31 tearing modulus at 300°C. The preliminary results indicate that the presence of high volume of δ-ferrite would noticeable impair fracture toughness although it may not influence hardness and tensile properties.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2019

Electrical, Structural, and Thermal Properties of Ferrite/Superconductor (Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}){sub x}/YBa{sub 2}Cu{sub 3}O{sub 7-δ}) Nanocomposite Materials

The superconductor YBa{sub 2}Cu{sub 3}O{sub 7-δ} (Y123) is prepared by the solid-state route, while the nanosized Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} (Ni-Zn ferrite) is synthesized via citric acid sol-gel technique. The composite material of the type (Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}){sub x}/YBa{sub 2}Cu{sub 3}O{sub 7-δ}, where x = 0.00, 0.03, 0.10, and 0.50 wt%, is prepared by a modified solid-state method to study the effect of doping Ni-Zn nanosized ferrite on the superconducting, structure, and thermal properties of Y123. The prepared samples show Meissner effect which confirmed the presence of superconducting phase at liquid nitrogen temperature (77 K). The prepared samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion of X-ray (EDX), infra-red (IR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), DC resistance by four-probe, and critical current density measurements. It was found that by increasing Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles in the Y123 compound, the unit cell volume of the orthorhombic phase decreases, but the transition temperature T{sub c} and critical current density J{sub c} decrease for low doping (x = 0.03 wt%) then increase (x = 0.10 and 0.50 wt%) for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} doped in Y123. The transport properties of the (Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}){sub x}/YBa{sub 2}Cu{sub 3}O{sub 7}-{sub δ} composite as electrical resistance R, T{sub c}, and J{sub c} are interpreted according to Bean’s critical state model and charge-vortex interaction combined with vortex pinning in Y123 high-T{sub c} mixed-state type-II superconductor. Highlights: The critical current density J{sub c} decreased for low doping of nanosized Ni-Zn ferrite into Y123 with ratio of 0.03 wt% and increased by increasing doping ratio to 0.50 wt%. The physical properties are improved by the coexistence of the superconductor Y123 and nanosized Ni-Zn ferrites in nanocomposite material.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2017

Fracture toughness evaluation of select advanced replacement alloys for LWR core internals

Life extension of the existing nuclear reactors imposes irradiation of high fluences to structural materials, resulting in significant challenges to the traditional reactor materials such as type 304 and 316 stainless steels. Advanced alloys with superior radiation resistance will increase safety margins, design flexibility, and economics for not only the life extension of the existing fleet but also new builds with advanced reactor designs. The Electric Power Research Institute (EPRI) teamed up with Department of Energy (DOE) to initiate the Advanced Radiation Resistant Materials (ARRM) program, aiming to develop and test degradation resistant alloys from current commercial alloy specifications by 2021 to a new advanced alloy with superior degradation resistance in light water reactor (LWR)-relevant environments by 2024. Fracture toughness is one of the key engineering properties required for core internal materials. Together with other properties, which are being examined such as high-temperature steam oxidation resistance, radiation hardening, and irradiation-assisted stress corrosion cracking resistance, the alloys will be down-selected for neutron irradiation study and comprehensive post-irradiation examinations. According to the candidate alloys selected under the ARRM program, ductile fracture toughness of eight alloys was evaluated at room temperature and the LWR-relevant temperatures. The tested alloys include two ferritic alloys (Grade 92 and an oxide-dispersion-strengthened alloy 14YWT), two austenitic stainless steels (316L and 310), four Ni-base superalloys (718A, 725, 690, and X750). Alloy 316L and X750 are included as reference alloys for low- and high-strength alloys, respectively. Compact tension specimens in 0.25T and 0.2T were machined from the alloys in the T-L and R-L orientations according to the product forms of the alloys. This report summarizes the final results of the specimens tested and analyzed per ASTM Standard E1820. Unlike the ferritic alloys showing slight decreases (Grade 92) or significant decreases (14YWT) in fracture toughness at elevated temperatures, the fracture toughness of the austenitic stainless steels and Ni-base superalloys were not strongly dependent upon the test temperatures. The fracture toughness of the alloys at the LWR-relevant temperatures was estimated by averaging the toughness values within 250– 350°C, which suggested the fracture toughness of the alloys in a descending order as 316L (752±98 MPa√m), 310 (513±66 MPa√m), 718A (313±43 MPa√m), 690 (267±48 MPa√m), 725 (218±55 MPa√m), X750 (145±16 MPa√m), Grade 92 (112±12 MPa√m), and 14YWT (63±3 MPa√m). Tearing modulus of the alloys was analyzed in the meantime, which were not strongly dependent upon the test temperatures. The high-strength alloys 718A, 725, X750, and 14YWT had the lowest tearing modulus, ranging from ~45 to ~7. Alloy 690 exhibited the highest tearing modulus on the order of 450, followed by 316L and 310 on the order of 260. Grade 92 had a noticeably lower tearing modulus on the order of 70.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Metallurgical aspects influencing the resistance to steam oxidation and fracture toughness of select advanced replacement alloys for LWR core internals

Life extension of the existing nuclear reactors imposes accumulated damages, such as higher fluences and longer period of corrosion, to structural materials, which would result in significant challenges to the traditional reactor materials such as type 304 and 316 stainless steels. Advanced alloys with superior radiation resistance will increase safety margins, design flexibility, and economics for not only the life extension of the existing fleet but also new builds with advanced reactor designs. The Electric Power Research Institute (EPRI) teamed up with Department of Energy (DOE) to initiate the Advanced Radiation Resistant Materials (ARRM) program, aiming to develop and test degradation resistant alloys from current commercial alloy specifications by 2021 to a new advanced alloy with superior degradation resistance in light water reactor (LWR)-relevant environments by 2024. Corrosion resistance in water environment is one of the fundamental properties required for LWR core internal materials. High-temperature steam oxidation tests are not only an accelerated life testing method to uncover potential failure modes in a short period of time, but also an approach to evaluate materials’ resistance to accidental scenarios. Coupons, prepared from fourteen candidate alloys that were selected under the ARRM program, were exposed to 1 bar full steam with ~10 part-per-billion oxygen content at 600 and 650°C for up to 5,000 h, which were weighed at 500-h intervals. Ni-base superalloys are an important class of alloys for reactor applications. Alloys 690, 725, and X- 750 were three of the selected Ni-base superalloys exposed to the steam tests. This report summarizes the metallurgical aspects, such as alloy thermodynamics and the nature of the oxides and the diffusivities of primary elements, and their effects on oxidation behavior of the three alloys. In addition to monitoring mass change, microstructures of the 5000h-exposed samples of alloys 690, 725, and X-750 were characterized using scanning and transmission electron microscopy and energy dispersive x-ray spectroscopy. Together with thermodynamic calculations, the scale constitution and its exfoliation behavior were discussed. Based on experimental and theoretical values, a new model was proposed to quantitatively estimate the metal thickness loss of the alloys. Alloy X-750 was found to have the best resistance to steam oxidation with the least metal thickness loss (<1 μm), which were slightly superior to alloy 690. Alloy 725 exhibited the worst resistance to steam oxidation with the greatest metal thickness loss, e.g., ~2.5 μm at 650°C, which is nearly three times of the metal thickness losses of alloys 690 and X-750 at 650°C. The greatest metal thickness loss of alloy 725 might be attributable to its high Mo content. Photos of the fracture toughness tested samples of eight alloys are presented, which will be correlated with their fracture toughness results and planned tensile test results to select representative alloy samples for detailed microstructural characterization to reveal their microstructure and properties relationships.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2026

Methods for Assessing Opportunities for Ring Dam Pumped Storage Hydropower

There is growing interest in new pumped storage hydropower (PSH) deployment to provide a range of grid flexibility, reliability, and resiliency services under an evolving and uncertain future power sector. The National Laboratory of the Rockies develops open PSH resource assessment and cost modeling tools to help evaluate PSH deployment opportunities, and this report describes expansions to those tools to consider an additional PSH system configuration - ring-dam reservoirs built on flat topographical features that are constructed from roller-compacted concrete material. This reservoir type is common among current PSH proposals and requires new methods to identify sites with this reservoir geometry throughout the United States and characterize the associated dam cost. Cost characterization for ring dam reservoirs required collecting historical dam cost data for earthen, rockfill, and roller-compacted concrete dams and regressing equations that relate costs between alternative materials. The ring dam site identification algorithm follows a 5-step procedure to identify circular geometry reservoirs. Once ring dam reservoirs are identified, they are then paired with potential dry-gully reservoirs, and the full set of potential paired reservoirs is cost-optimized to produce a least-cost set of potential PSH sites with no overlapping reservoirs. The resulting analysis found 1,663 ring-dam to dry-gully systems in the contiguous United States that are lower cost than any overlapping dry-gully to dry-gully systems, 29 in Alaska, and none in Hawaii or Puerto Rico. These systems constitute 1.5 TW of capacity in the contiguous United States and nearly 29 GW in Alaska, demonstrating that under suitable topography and head, ring-dam systems can provide cost-effective PSH opportunities. The greatest density of these opportunities are found in the intermountain west where there are mesas and flat land at bases of mountain ranges, but continued work could incorporate additional site characteristics or consider more complex reservoir shapes to find additional PSH deployment opportunities.

13 HYDRO ENERGY↗

DOE OSTI2018

Modular DNA strand-displacement controllers for directing material expansion

Abstract Soft materials that swell or change shape in response to external stimuli show extensive promise in regenerative medicine, targeted therapeutics, and soft robotics. Generally, a stimulus for shape change must interact directly with the material, limiting the types of stimuli that may be used and necessitating high stimulus concentrations. Here, we show how DNA strand-displacement controllers within hydrogels can mediate size change by interpreting, amplifying, and integrating stimuli and releasing signals that direct the response. These controllers tune the time scale and degree of DNA-crosslinked hydrogel swelling and can actuate dramatic material size change in response to <100 nM of a specific biomolecular input. Controllers can also direct swelling in response to small molecules or perform logic. The integration of these stimuli-responsive materials with biomolecular circuits is a major step towards autonomous soft robotic systems in which sensing and actuation are implemented by biomolecular reaction networks.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2017

Shock waves simulated using the dual domain material point method combined with molecular dynamics

Here in this work we combine the dual domain material point method with molecular dynamics in an attempt to create a multiscale numerical method to simulate materials undergoing large deformations with high strain rates. In these types of problems, the material is often in a thermodynamically nonequilibrium state, and conventional constitutive relations or equations of state are often not available. In this method, the closure quantities, such as stress, at each material point are calculated from a molecular dynamics simulation of a group of atoms surrounding the material point. Rather than restricting the multiscale simulation in a small spatial region, such as phase interfaces, or crack tips, this multiscale method can be used to consider nonequilibrium thermodynamic effects in a macroscopic domain. This method takes the advantage that the material points only communicate with mesh nodes, not among themselves; therefore molecular dynamics simulations for material points can be performed independently in parallel. The dual domain material point method is chosen for this multiscale method because it can be used in history dependent problems with large deformation without generating numerical noise as material points move across cells, and also because of its convergence and conservation properties. In conclusion, to demonstrate the feasibility and accuracy of this method, we compare the results of a shock wave propagation in a cerium crystal calculated using the direct molecular dynamics simulation with the results from this combined multiscale calculation.

36 MATERIALS SCIENCE↗

DOE OSTI2016

TH-CD-BRA-04: Effect of a Strong Magnetic Field On TLDs, OSLDs, and Gafchromic Films Using An Electromagnet

Purpose: To study the effect of strong magnetic field on three types of dosimeters using an electromagnet inside a Linac vault. Materials and Methods: Three types of dosimeters, thermoluminescent Dosimeters (TLDs), optically stimulated luminescent Dosimeters (OSLDs), and EBT3 Film were used to measure radiation dose response inside an electromagnet that could produce a strong magnetic field (B>1.5 T). The dosimeters were placed inside a plastic phantom between the two poles of the magnet, at approximately 3 meters from the iso-center of an Elekta Versa HD Linac. The B field was calibrated with a Gauss meter (Model: GM-2, AlphaLab Inc). The dosimeters received ∼2 Gy with and without the presence of the 1.5 T magnetic field. The EBT3 films were scanned 24 hours before and 24 hours after irradiation. The TLD dosimeters were read 1 week after irradiation. The OSLDs were read two weeks after irradiation. The ratios of signals of dosimeters irradiated with the B field to the signals without the B field were calculated. Two experiments have been conducted so far. Results: The ratios (averaged over two experiments) of dosimeter signals with vs without B field were 0.994 for films, 0.994 for OSLDs, and 1.002 for TLDs. The statistical uncertainty was ∼3%. Conclusions: The three types of dosimeters (film, TLD, OSLD) seem not affected by the presence of a magnetic field (B=1.5 T) with the uncertainty of ∼3%. They may be suitable for QA purposes in a strong B field up to 1.5 T. More measurements will be conducted for reproducibility testing. We acknowledge research support from Elekta AB.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2017

Multi-scale calculation based on dual domain material point method combined with molecular dynamics

This dissertation combines the dual domain material point method (DDMP) with molecular dynamics (MD) in an attempt to create a multi-scale numerical method to simulate materials undergoing large deformations with high strain rates. In these types of problems, the material is often in a thermodynamically non-equilibrium state, and conventional constitutive relations are often not available. In this method, the closure quantities, such as stress, at each material point are calculated from a MD simulation of a group of atoms surrounding the material point. Rather than restricting the multi-scale simulation in a small spatial region, such as phase interfaces, or crack tips, this multi-scale method can be used to consider non-equilibrium thermodynamic e ects in a macroscopic domain. This method takes advantage that the material points only communicate with mesh nodes, not among themselves; therefore MD simulations for material points can be performed independently in parallel. First, using a one-dimensional shock problem as an example, the numerical properties of the original material point method (MPM), the generalized interpolation material point (GIMP) method, the convected particle domain interpolation (CPDI) method, and the DDMP method are investigated. Among these methods, only the DDMP method converges as the number of particles increases, but the large number of particles needed for convergence makes the method very expensive especially in our multi-scale method where we calculate stress in each material point using MD simulation. To improve DDMP, the sub-point method is introduced in this dissertation, which provides high quality numerical solutions with a very small number of particles. The multi-scale method based on DDMP with sub-points is successfully implemented for a one dimensional problem of shock wave propagation in a cerium crystal. The MD simulation to calculate stress in each material point is performed in GPU using CUDA to accelerate the computation. The numerical properties of the multiscale method are investigated as well as the results from this multi-scale calculation are compared of particles needed for convergence makes the method very expensive especially in our multi-scale method where we calculate stress in each material point using MD simulation. To improve DDMP, the sub-point method is introduced in this dissertation, which provides high quality numerical solutions with a very small number of particles. The multi-scale method based on DDMP with sub-points is successfully implemented for a one dimensional problem of shock wave propagation in a cerium crystal. The MD simulation to calculate stress in each material point is performed in GPU using CUDA to accelerate the computation. The numerical properties of the multiscale method are investigated as well as the results from this multi-scale calculation are compared with direct MD simulation results to demonstrate the feasibility of the method. Also, the multi-scale method is applied for a two dimensional problem of jet formation around copper notch under a strong impact.

74 ATOMIC AND MOLECULAR PHYSICS↗

NASA NTRSDate not supplied

Fabrication and Characterization of A Lunar Simulant-Based Sintered Construction Material

In-situ resource utilization (ISRU) is critical to enable future efforts to have a long-term human presence on the Moon as well as Mars. ISRU technologies are being developed for radiation protection, dust mitigation, thermal insulation, and other applications. One such ISRU technology for creating construction materials out of lunar and Martian regolith is sintering, which is a thermal-based construction process that bonds finely grained material together at temperatures below the melting point. However, the conditions employed during the sintering, such as temperature, atmospheric composition, duration of the process, and pressure, can have a significant impact on the quality and strength of the resulting materials. In parallel, the development of methods for characterizing the quality, porosity, density, and other properties of these materials is critical. X-ray computed tomography (X-ray CT) can image large changes in density within a material, such as the presence of pores throughout an otherwise uniform medium, with relatively high spatial resolution. Similarly, Terahertz time-domain spectroscopic (THz-TDS) imaging is sensitive to density variations within samples, but is restricted to non-conducting materials. Specifically, previous work has shown that the refractive index (n eff ) values obtained through the analysis of THz-TDS images increases with increasing density within plastic samples. Even further, this work showed that it is possible to create a calibration curve for a given material from samples of different, but known density, which can enable one to directly convert n eff to density for samples having the same composition, but unknown density. Here, we report on the fabrication of a lunar simulant-based sintered construction material using vacuum hot pressed (VHP) sintering, then show X-ray CT and THz-TDS imaging results of the sample, which show spatial variations in the material. This has important implications for efforts to improve these types of lunar construction material processes and verify the quality of these materials in terms of consolidation. To the best of our knowledge, there is no previous work utilizing VHP sintering to make lunar simulant-based construction materials or exploring the feasibility of THz imaging to spatially map the density variation through a lunar simulant-based construction material.

Terahertz time-domain spectroscopic imaging↗

DOE OSTI2021

Research on Bulk-metallic Glasses and High-entropy Alloys in Peter K. Liaw’s Group and with His Colleagues

Bulk-metallic glasses (BMGs) and high-entropy alloys (HEAs) have attracted extensive attention in the field of metallic materials research for several decades due to their extraordinary properties. Many scientists and researchers have significantly contributed to developing new classes of metallic alloys, such as BMGs and HEAs, for various applications. Liaw’s group and his colleagues have focused on the fundamental understanding of unique features, structures, and properties in BMGs and HEAs as well as the development of new types of metallic materials. Here, we summarized the research work of Liaw’s group and his colleagues by reviewing relevant papers. The goal is to provide an understanding of the current research progression in BMGs and HEAs while further encouraging young and junior researchers to be involved in the field of structural materials research pertaining to these classes of exotic alloy systems.

36 MATERIALS SCIENCE↗