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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Electrical Resistivity Tomography Monitoring of In Situ Soil Flushing at the Hanford 100-K East Area: 100KE Soil Flushing Monitoring

Former operations in the 100-KE Area at the Hanford Site resulted in vadose zone hexavalent chromium that provides a source of groundwater contamination. Previous efforts to remediate vadose zone chromium involved excavation and offsite treatment of contaminated soils. Although much of the chromium was removed, contamination still exists in native soil between the water table and the bottom of the pit, which has since been backfilled. In-situ soil flushing was tested at the 100-KE Area to accelerate the removal of the remaining hexavalent chromium in the vadose zone. Soil flushing works by applying clean flush water at the surface, which mobilizes and transports chromium as it migrates downward to the water table. Once the chromium reaches the water table, it is hydraulically contained, extracted, and treated through pump and treat operations. The efficacy of soil flushing is directly related to the volume of clean water that infiltrates through contaminated soils. Therefore, performance monitoring requires and understanding of flush water migration through the vadose zone. It is challenging to comprehensively assess soil flushing performance via borehole access due to the limited volume of investigation afforded by a given wellbore. As an alternative, 3D time-lapse electrical resistivity tomography (ERT) was tested as a method of monitoring the distribution of flush water over time within the vadose zone. ERT is a method of imaging the bulk electrical conductivity of the subsurface, which is highly dependent on water saturation levels in unconsolidated and unsaturated sediments. Thus, the timing and location of changes in bulk conductivity caused by soil flushing can be used to infer flush water migration pathways. In this report we present results of 3D time-lapse ERT imaging during two separate soil flushing campaigns conducted during the spring and summer months of 2022 and 2023. Results show generally that: 1) Pit backfill materials appear to nominally have larger permeability than native soils. Consequently, the boundary between pit backfill and native soil had a significant impact on flush water migration, causing some flush water to migrate along the pit boundary to the bottom of the pit. 2) Non-uniform flows, likely caused by variations in hydrogeologic properties, developed in the pit backfill materials, resulting in uneven flush water distribution on the southern margin of the soil flushing zone. 3) Redistribution of water at the interface between backfill materials and Hanford formation materials likely facilitated elevated and uniform distribution of flush water within native soils beneath the deeper parts of the pit boundary beneath the center of the flush zone, which presumably overlie soils with elevated chromium contamination. These areas appear to have been infiltrated by higher volumes of flush water than the northern and southern margins of the flush zone. 4) In comparison to 2022, high flush water application rates significantly improved flush water distribution throughout the target flushing zone. 5) Imaging resolution was limited to a depth of approximate 20 meters below the land surface, due primarily to limitations on the lateral extent of the surface ERT array. The ~10 m region of the vadose zone between approximately 130 meters elevation and the water table at approximately 120 meters elevation was unresolved.

100 Area↗
NASA NTRS1990

The structure and formation of natural categories

Categorization and concept formation are critical activities of intelligence. These processes and the conceptual structures that support them raise important issues at the interface of cognitive psychology and artificial intelligence. The work presumes that advances in these and other areas are best facilitated by research methodologies that reward interdisciplinary interaction. In particular, a computational model is described of concept formation and categorization that exploits a rational analysis of basic level effects by Gluck and Corter. Their work provides a clean prescription of human category preferences that is adapted to the task of concept learning. Also, their analysis was extended to account for typicality and fan effects, and speculate on how the concept formation strategies might be extended to other facets of intelligence, such as problem solving.

Fisher, Douglas↗
NASA NTRS1999

STS-99 SRTM Lift and Insert into Canister

The primary objective of the STS-99 mission was to complete high resolution mapping of large sections of the Earth's surface using the Shuttle Radar Topography Mission (SRTM), a specially modified radar system. This radar system produced unrivaled 3-D images of the Earth's Surface. The mission was launched at 12:31 on February 11, 2000 onboard the space shuttle Endeavour. and led by Commander Kevin Kregel. The crew was Pilot Dominic L. Pudwill Gorie and Mission Specialists Janet L. Kavandi, Janice E. Voss, Mamoru Mohri from the National Space Development Agency (Japanese Space Agency), and Gerhard P. J. Thiele from DARA (German Space Agency). This videotape shows clean room technicians working on a part of the 200 foot long mast that will hold the SRTM in position during the mission. This videotape also shows the lowering of the SRTM into the canister.

Source record↗
NASA NTRS2016

Evolution of the Lunar Receiving Laboratory to the Astromaterial Sample Curation Facility: Technical Tensions Between Containment and Cleanliness, Between Particulate and Organic Cleanliness

The Lunar Receiving Laboratory (LRL) was planned and constructed in the 1960s to support the Apollo program in the context of landing on the Moon and safely returning humans. The enduring science return from that effort is a result of careful curation of planetary materials. Technical decisions for the first facility included sample handling environment (vacuum vs inert gas), and instruments for making basic sample assessment, but the most difficult decision, and most visible, was stringent biosafety vs ultra-clean sample handling. Biosafety required handling of samples in negative pressure gloveboxes and rooms for containment and use of sterilizing protocols and animal/plant models for hazard assessment. Ultra-clean sample handling worked best in positive pressure nitrogen environment gloveboxes in positive pressure rooms, using cleanable tools of tightly controlled composition. The requirements for these two objectives were so different, that the solution was to design and build a new facility for specific purpose of preserving the scientific integrity of the samples. The resulting Lunar Curatorial Facility was designed and constructed, from 1972-1979, with advice and oversight by a very active committee comprised of lunar sample scientists. The high precision analyses required for planetary science are enabled by stringent contamination control of trace elements in the materials and protocols of construction (e.g., trace element screening for paint and flooring materials) and the equipment used in sample handling and storage. As other astromaterials, especially small particles and atoms, were added to the collections curated, the technical tension between particulate cleanliness and organic cleanliness was addressed in more detail. Techniques for minimizing particulate contamination in sample handling environments use high efficiency air filtering techniques typically requiring organic sealants which offgas. Protocols for reducing adventitious carbon on sample handling surfaces often generate particles. Further work is needed to achieve both minimal particulate and adventitious carbon contamination. This paper will discuss these facility topics and others in the historical context of nearly 50 years' curation experience for lunar rocks and regolith, meteorites, cosmic dust, comet particles, solar wind atoms, and asteroid particles at Johnson Space Center.

Allton, J. H.↗
DOE OSTI2020

Radioactive Cleaning Robot

Here at Fermi, work is centered around particle accelerators. With the functionality of these accelerators comes a small amount of radioactive dust. For the sake of all employees in this environment, a yearly deep clean is necessary. The aim of this robot is to save time by running an automated cleaning robot 24/7.

Stachowicz, Emily↗
NASA NTRS2014

Alternative, Green Processes for the Precision Cleaning of Aerospace Hardware

Precision cleaning is necessary to ensure the proper functioning of aerospace hardware, particularly those systems that come in contact with liquid oxygen or hypergolic fuels. Components that have not been cleaned to the appropriate levels may experience problems ranging from impaired performance to catastrophic failure. Traditionally, this has been achieved using various halogenated solvents. However, as information on the toxicological and/or environmental impacts of each came to light, they were subsequently regulated out of use. The solvent currently used in Kennedy Space Center (KSC) precision cleaning operations is Vertrel MCA. Environmental sampling at KSC indicates that continued use of this or similar solvents may lead to high remediation costs that must be borne by the Program for years to come. In response to this problem, the Green Solvents Project seeks to develop state-of-the-art, green technologies designed to meet KSCs precision cleaning needs.Initially, 23 solvents were identified as potential replacements for the current Vertrel MCA-based process. Highly halogenated solvents were deliberately omitted since historical precedents indicate that as the long-term consequences of these solvents become known, they will eventually be regulated out of practical use, often with significant financial burdens for the user. Three solvent-less cleaning processes (plasma, supercritical carbon dioxide, and carbon dioxide snow) were also chosen since they produce essentially no waste stream. Next, experimental and analytical procedures were developed to compare the relative effectiveness of these solvents and technologies to the current KSC standard of Vertrel MCA. Individually numbered Swagelok fittings were used to represent the hardware in the cleaning process. First, the fittings were cleaned using Vertrel MCA in order to determine their true cleaned mass. Next, the fittings were dipped into stock solutions of five commonly encountered contaminants and were weighed again showing typical contaminant deposition levels of approximately 0.00300g per part. They were then cleaned by the solvent or process being tested and then weighed a third time which allowed for the calculation of the cleaning efficiency of the test solvent or process.Based on preliminary experiments, five solvents (ethanol, isopropanol, acetone, ethyl acetate, and tert-butyl acetate) were down selected for further testing. When coupled with ultrasonic agitation, these solvents removed hydrocarbon contaminants as well as Vertrel MCA and showed improved removal of perfluorinated greases. Supercritical carbon dioxide did an excellent job dissolving each of the five contaminants but did a poor job of removing Teflon particles found in the perfluorinated greases. Plasma cleaning efficiency was found to be dependent on which supply gas was used, exposure time, and gas pressure. Under optimized conditions it was found that breathing air, energized to the plasma phase, was able to remove nearly 100% of the contamination.These findings indicate that alternative cleaning methods are indeed able to achieve precision levels of cleanliness. Currently, our team is working with a commercial cleaning company to get independent verification of our results. We are also evaluating the technical and financial aspects of scaling these processes to a size capable of supporting the future cleaning needs of KSC.

Vertrel MCA↗
DOE OSTI2021

Mastering Medaka Culture: Improved Techniques for Increasing Egg and Fry Production in Japanese Rice Fish ( Oryzias latipes )

Aquatic systems are integral to ecosystem function and human health. By trapping sediments and retaining nutrients, wetlands protect our water quality. However, a wetland’s capacity to trap sediments and nutrients also means they can capture many contaminants (e.g., heavy metals and radionuclides) released into the environment due to anthropogenic activities. Both heavy metals and radionuclides have detrimental effects on wildlife at acute dosages. However, little is known regarding underlying biological responses associated with chronic low dose exposure to both ionizing radiation and heavy metals. Our long-term research goal is to work to fill this knowledge gap using Medaka (Oryzias latipes), small fish amenable to experimental manipulation. However, the current study focused on altering the husbandry protocol of a laboratory colony of Medaka in a way that would increase colony size to at least 400 individual fish over a six-week period. At the beginning of our work, we followed a strict cleaning, feeding and egg harvesting protocol. Two weeks into our work, we suspected that food limitations may be negatively impacting egg production and noticed fungal growth on eggs. Thus, we altered the feeding regime and egg harvesting protocol. The altered protocol more than tripled egg production and almost doubled of fry production. By the end of our study the colony had 673 individuals: 191 adults and 482 fry. Furthermore, our protocol changes resulted in growth of the colony at sufficient numbers to begin experiments related to investigating sub-lethal impacts of heavy metals and radionuclides on Medaka.

Thompson, Melissa↗
DOE OSTI2021

NUMERICAL CALCULATION OF LOSSES OF TRAPPED VORTICES UNDER STRONG RF MEISSNER CURRENT AND DC SUPERHEATING FIELD IN TYPE II SUPERCONDUCTORS

Research on the vortex dynamics and enhancing of superheating field in superconductors has attracted much attention in accelerator physics community to develop next-generation high-performance accelerator cavities. However, the extreme dynamics of curvilinear elastic vortices driven by very strong currents close to the depairing limit or superheating field of a superconductor with a nanostructured surface has not been well understood. We calculated the superheating field Hsh and critical momentum kc characterizing the wavelength of the instability ?m of the Meissner state to flux penetration by solving numerically the Ginzburg?Landau equations. A bulk superconductor, superconductor with the inhomogeneous surface disorder (S-S), and multilayered surface (S-I-S) have been thoroughly investigated in this work. Our result showed that S-S and S-I-S structures can enhance the superheating field well above their clean limit. In this work extensive numerical simulation of the power dissipated by an oscillating vortex segment driven by the surface ac Meissner currents was performed. Our simulations take into account the nonlinear vortex line tension, vortex mass, Bardeen?Stephen viscous vortex drag applicable at low fields, and nonlinear Larkin-Ovchinnikov (LO) viscous drag coefficient ?(v) at high fields and pinning force. We showed that the LO decrease of ?(v) with the vortex velocity v could radically change the field dependence of the surface resistance Ri(H) caused by trapped vortices. At low frequencies Ri(H) exhibits a conventional increase with H. However, as frequency increases, the surface resistance becomes a nonmonotonic function of H which decreases with H at higher fields irrespective of the pinning distribution. Overheating can mask the descending field dependence of Ri(H) as frequency increases. Our numerical simulations also show that the LO effect can cause a vortex bending instability at high field amplitudes and frequencies, giving rise to the formation of dynamic kinks along with the vortex when a vortex is pinned strongly to one end. Nonlinear losses of trapped vortices in thick films under high-amplitude RF fields as functions of frequency, mean free path and pinning characteristics have been calculated.

Pathirana, Walive↗
DOE OSTI2023

Influence of Application Method on Disinfectant Byproduct Formation during Indoor Bleach Cleaning: A Case Study on Phenol Chlorination

Modern disinfection methods increasingly utilize droplet dispersal as a means of delivering disinfectant within an indoor space. Such an application produces droplets over wide size ranges, some of which may remain airborne for minutes to hours while serving as small reaction environments. We report here the formation of chlorophenolic disinfection byproducts (DBPs) during the injection of bleach microdroplets into an environmental chamber. These reactions within airborne microdroplets are driven by phenol dissolution and availability, and the observed DBPs span multiple generations of chlorination chemistry. DBPs representing successive chlorine addition to the phenol ring are initially observed (mono-, di-, and trichlorophenol), followed by DBPs that lack aromaticity (2,6-dichlorobenzoquinone and 2,4,4,6-tetrachloro-2,5-cyclohexadienone, among others). Chlorophenolic DBPs have not been reported during prior work examining indoor bleach cleaning and we attribute their observation in this work to the dispersal of disinfectant microdroplets rather than traditional mopping or wiping with a bulk aqueous solution on an indoor surface. Airborne microdroplets represent unique reaction and volatilization environments and unique exposure pathways to DBPs, via direct compound inhalation as well as the inhalation of DBP-containing microdroplets. The observed DBPs (particularly 2,6-dichlorobenzoquinone) have previously been linked to adverse health effects in humans through either direct toxicity or as precursors to other DBPs with adverse health effects. In conclusion, these measurements suggest that more work is needed to understand potential DBP formation and human exposure within a variety of indoor environments where disinfection techniques that generate airborne microdroplets are used.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Megawatt-Scale Low Temperature Electrolyzer Research Expansion

The development and installation of a flexible low-temperature electrolyzer research capability at the multi-MW scale with integrated renewables will help lower the cost barrier to entry for electrolyzer manufactures needing at scale system and stack evaluation and enable more electrolyzer manufactures to accelerate to commercialization with building block scale demonstration and validation. This NREL capability represents a DOE HFTO investment to support the $1B DOE Clean Hydrogen Electrolysis Program working to achieve the Hydrogen Shot goal of $1 for 1 kg hydrogen in 1 decade, lower greenhouse gas emissions and criteria pollutants, build clean energy infrastructure, and provide pathways to private sector uptake.

Advanced Research on Integrated Energy Systems (AR↗
DOE OSTI2024

Megawatt-Scale Low Temperature Electrolyzer Research Capability

The development and installation of a flexible low-temperature electrolyzer research capability at the multi-MW scale with integrated renewables will help lower the cost barrier to entry for electrolyzer manufactures needing at scale system and stack evaluation and enable more electrolyzer manufactures to accelerate to commercialization with building block scale demonstration and validation. This NREL capability represents a DOE HFTO investment to support the $1B DOE Clean Hydrogen Electrolysis Program working to achieve the Hydrogen Shot goal of $1 for 1 kg hydrogen in 1 decade, lower greenhouse gas emissions and criteria pollutants, build clean energy infrastructure, and provide pathways to private sector uptake.

electrical grid↗
DOE OSTI2024

Kansas City, Missouri, Streetlight Electric Vehicle Charging: Strategies and challenges for site selection of streetlight electric vehicle infrastructure in Kansas City, Missouri (Final Report)

Public streetlight charging, whether on streets in central business districts or residential areas, provides easy charging access for apartment residents and homeowners alike. While most electric vehicle (EV) drivers charge at home, they do so in garages or on driveways they own. For renters and residents of multifamily housing (MFH), however, this may not be an option. EVs have a lower cost of ownership compared to conventional vehicles, and a used EV may be an affordable option for a lower-income household. But without easy access to charging, even a low-cost used EV may not be an option for a prospective buyer. An affordable curbside charging network has the potential to expand EV adoption into neighborhoods that have to date seen minimal interest and uptake of the technology and associated charging infrastructure. Streetlight charging networks can provide an economical, scalable, and effective approach to providing equitable and convenient charging. Metropolitan Energy Center (MEC) is dedicated to the mission of creating resource efficiency, environmental health, and economic vitality in the Kansas City region and beyond. Since 1983, MEC has provided resources, outreach, and training to make alternative fuels and energy efficiency commonplace. MEC led a streetlight charging pilot project that installed limited EV charging infrastructure on the streetlight system in Kansas City, Missouri, to demonstrate and test the benefits of curbside charging for EVs at existing on-street parking locations. The project aimed to cost-effectively expand the charging network in Kansas City to support residential charging and provide infrastructure in one or more charging deserts throughout the city. This pilot evaluates the impact and overall success of streetlight charging based on community feedback, utilization of charging infrastructure, technical feasibility, and cost. The project has pursued a data- and community-driven site selection process designed to identify sites with high demand and high opportunity for EV charging. This project was funded by the U.S. Department of Energy (DOE) and awarded to MEC through a competitive proposal process. The novelty and complexity of this project required an organization that could facilitate collaboration across levels of government, community members, and industry partners. For the past 25 years, through Kansas City Regional Clean Cities, MEC has worked with numerous public and private fleets on a variety of projects to improve the environmental performance and efficiency of the regional vehicle fleet. To advance affordable, efficient, and clean transportation efforts, DOE Clean Cities and Communities coalitions create local networks of public and private sector stakeholders and engage communities. Rooted within their local communities, the coalitions serve as experts and ambassadors, bringing to bear the collective knowledge, experience, and practical know-how of the entire network from within DOE, its national laboratories, and diverse stakeholders in the field. MEC and its project partners made in-kind contributions to leverage federal dollars for the benefit of the Kansas City community. Findings from this project will help determine the best applications for streetlight charging technologies to maximize funding impact and serve community needs. The team evaluated locations based on expected charging demand, technical feasibility, safety considerations, and enhanced charging network siting needs. Throughout the project, the team gathered feedback and evaluated ways to make public charging for EVs available to all community members. The insights will help Kansas City and other communities streamline future efforts to support EV drivers through public charging in the city right-of-way. Furthermore, this project will inform citywide guidance for future installations. MEC is committed to a transparent and publicly accessible approach that encourages the collaborative evaluation of streetlight charging. The project has engaged the community to proactively identify and evaluate the benefits and impacts of streetlight charging. It was a priority for the project to ensure the benefits of this pilot are distributed equitably to all members of the Kansas City community and that new charging opportunities and associated resources are available in diverse neighborhoods across the city. The charging infrastructure supports an affordable curbside charging network that will enable more drivers to choose EVs and provide easy charging access for all community members interested in driving an EV. The community feedback received through this project informed future resources and opportunities to make EVs more accessible to all members of the Kansas City community. MEC worked with several community partners on this project, including Missouri University of Science and Technology (MST), Pennsylvania State University (Penn State), the National Renewable Energy Laboratory (NREL); the city of Kansas City, Missouri; Evergy; Black and McDonald (B&M); LilyPad EV; EVNoire; and Westside Housing Organization (WHO). Project partners contributed to the cost match required for DOE grants through capital expenditures, personnel, and other in-kind contributions. Detailed descriptions of project team organizations can be found in Appendix A. Project Partners. Analysts at NREL and MST/PennState developed site maps based on demand and equity considerations. MEC conducted outreach to community members to garner input on project design and site selection, and received approval from the Missouri Public Service Commission (PSC) for Evergy’s EV charging station ownership. MEC worked with all partners to gather additional siting criteria and developed a site selection evaluation checklist, and partners conducted site visits to proposed installation sites. Next, B&M, Evergy, and the city executed all site agreements, conducted site-specific engineering design, acquired associated permits, and issued notices to proceed site by site or in small batches. Finally, from January to April 2023, the project team installed 23 EV charging stations built on Kansas City’s streetlight system in six council districts. Evergy will own, operate, and monitor the stations for 10 years, sharing charging data with MEC for at least 1 year.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Developing and tuning a community scale energy model for a disadvantaged community

This work describes the development of a community-scale energy model for a mixed-use low-income community located in Huntington Beach, CA. An accurate community-scale energy model is useful for evaluating the use of limited capital resources used to invest in clean energy technologies. This work lays out the process of developing such a model while relying primarily on publicly available data and highlighting critical partnerships necessary for model development success. The primary contribution of this work is the demonstration of the process used to develop an accurate energy model for a disadvantaged community when minimal building and energy use data is available. The heart of the model is the physics-based community scale energy modeling platform URBANopt. Using a bottom-up load modeling approach, energy simulated energy use falls within 3% or less of aggregate annual utility data, and within 10% or less aggregate monthly utility data. The demonstrated model development and tuning process can be used by others to characterize other atypical communities, which may differ significantly from prototypical models.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS2004

JDD, Inc. Database

JDD Inc, is a maintenance and custodial contracting company whose mission is to provide their clients in the private and government sectors "quality construction, construction management and cleaning services in the most efficient and cost effective manners, (JDD, Inc. Mission Statement)." This company provides facilities support for Fort Riley in Fo,rt Riley, Kansas and the NASA John H. Glenn Research Center at Lewis Field here in Cleveland, Ohio. JDD, Inc. is owned and operated by James Vaughn, who started as painter at NASA Glenn and has been working here for the past seventeen years. This summer I worked under Devan Anderson, who is the safety manager for JDD Inc. in the Logistics and Technical Information Division at Glenn Research Center The LTID provides all transportation, secretarial, security needs and contract management of these various services for the center. As a safety manager, my mentor provides Occupational Health and Safety Occupation (OSHA) compliance to all JDD, Inc. employees and handles all other issues (Environmental Protection Agency issues, workers compensation, safety and health training) involving to job safety. My summer assignment was not as considered "groundbreaking research" like many other summer interns have done in the past, but it is just as important and beneficial to JDD, Inc. I initially created a database using a Microsoft Excel program to classify and categorize data pertaining to numerous safety training certification courses instructed by our safety manager during the course of the fiscal year. This early portion of the database consisted of only data (training field index, employees who were present at these training courses and who was absent) from the training certification courses. Once I completed this phase of the database, I decided to expand the database and add as many dimensions to it as possible. Throughout the last seven weeks, I have been compiling more data from day to day operations and been adding the information to the database. It now consists of seven different categories of data (carpet cleaning, forms, NASA Event Schedules, training certifications, wall and vent cleaning, work schedules, and miscellaneous) . I also did some field inspecting with the supervisors around the site and was present at all of the training certification courses that have been scheduled since June 2004. My future outlook for the JDD, Inc. database is to have all of company s information from future contract proposals, weekly inventory, to employee timesheets all in this same database.

Miller, David A., Jr.↗
NASA NTRS2021

Components Cleaning Facility, SWMU 030 Eastern High-Concentration Plume Area Implementation Work Plan Kennedy Space Center, Florida

This Implementation Work Plan (IWP) presents detailed design elements and coordination specifics to implement an air sparging (AS) Interim Measure (IM) to remediate groundwater at the Components Cleaning Facility (CCF), Eastern High Concentration Plume (HCP) Area located at Kennedy Space Center (KSC), Florida. The objective of the CCF East IM is to remediate groundwater where trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations exceed Florida Department of Environmental Protection Natural Attenuation Default Criteria (NADC) (identified as the HCP) via AS and to transition to monitored natural attenuation. CCF has been designated Solid Waste Management Unit 030 under KSC’s Resource Conservation and Recovery Act Corrective Action Program.

James Lloyd↗
DOE OSTI2023

Theory of electric, magnetic, and toroidal polarizations in crystalline solids with applications to hexagonal lonsdaleite and cubic diamond

Multipolar order in bulk crystalline solids is characterized by multipole densities-denoted as polarizations in this work-that cannot be cleanly defined using the concepts of classical electromagnetism. Here we use group theory to overcome this difficulty and present a systematic study of electric, magnetic, and toroidal multipolar order in crystalline solids. Based on our symmetry analysis, we identify five categories of polarized matter, each of which is characterized by distinct features in the electronic band structure. For example, Rashba spin splitting in electropolar bulk materials like wurtzite represents the electric dipolarization in these materials. We also develop a general formalism of indicators for individual multipole densities that provide a physical interpretation and quantification of multipolar order. Our work clarifies the relation between patterns of localized multipoles and macroscopic multipole densities they give rise to. To illustrate the general theory, we discuss its application to polarized variants of hexagonal lonsdaleite and cubic diamond structures. In conclusion, our work provides a general framework for classifying and expanding current understanding of multipolar order in complex materials.

36 MATERIALS SCIENCE↗