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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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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Windowless Optical Cell Flow System

One of the goals for advanced integrated nuclear safeguards is on-line optical analysis of molten salt in molten salt reactors and electrochemical fuel reprocessing facilities. While progress has been made in the development of optical techniques that may be suitable for on-line analysis of molten salts, significant technology gaps exist with regard to integrating these analytical techniques into industrial-scale processes. One key technological hurdle is the short service life of optical window materials, which are subject to clouding and scaling during extended exposure to molten salts. To address this issue, Argonne is developing a gravity flow cell with open-apertures to support on-line optical analysis without the need for salt-wetted windows. The flow cell uses gravity flow and fluid dynamics principles to enable molten salt flow through a pipe that has holes in its wall through which salt does not flow. In FY21, an open-aperture gravity flow cell with windowless optical access to flowing salt was successfully demonstrated. Future work should include the integration of the flow cell into a sampling loop, stakeholder outreach and collaboration, integration of multiple optical analysis techniques, evaluation of the integrated methods, and analyses to determine how the various tools might fit into an integrated safeguards monitoring system of unattended near real time monitoring tools.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

A meta-evaluation of the quality of reporting and execution in ecological meta-analyses

Quantitatively summarizing results from a collection of primary studies with meta-analysis can help answer ecological questions and identify knowledge gaps. The accuracy of the answers depends on the quality of the meta-analysis. We reviewed the literature assessing the quality of ecological meta-analyses to evaluate current practices and highlight areas that need improvement. From each of the 18 review papers that evaluated the quality of meta-analyses, we calculated the percentage of meta-analyses that met criteria related to specific steps taken in the meta-analysis process (i.e., execution) and the clarity with which those steps were articulated (i.e., reporting). We also re-evaluated all the meta-analyses available from Pappalardo et al. to extract new information on ten additional criteria and to assess how the meta-analyses recognized and addressed non-independence. In general, we observed better performance for criteria related to reporting than for criteria related to execution; however, there was a wide variation among criteria and meta-analyses. Meta-analyses had low compliance with regard to correcting for phylogenetic non-independence, exploring temporal trends in effect sizes, and conducting a multifactorial analysis of moderators (i.e., explanatory variables). In addition, although most meta-analyses included multiple effect sizes per study, only 66% acknowledged some type of non-independence. The types of non-independence reported were most often related to the design of the original experiment (e.g., the use of a shared control) than to other sources (e.g., phylogeny). We suggest that providing specific training and encouraging authors to follow the PRISMA EcoEvo checklist recently developed by O’Dea et al. can improve the quality of ecological meta-analyses.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Energy Analysis of Combi Heat Pump System Configurations for Space Conditioning and Domestic Hot Water Heating in Residential Buildings

Combi heat pump systems, also referred to multifunctional variable refrigerant flow heat recovery (MF-VRFHR) systems, are specifically designed for residential applications to manage both space conditioning and domestic hot water (DHW). They have attracted attention due to their potential for energy conservation through heat recovery. The incorporation of a hot water tank introduces various system configurations, each characterized by distinct pros and cons related to energy efficiency, system stability, and maintenance. Despite this, a critical gap exists as the specific energy performance remains unquantified under diverse operational modes (e.g., heating mode and heat recovery mode). This paper aims to bridge this gap by conducting a comprehensive comparative analysis of two prevalent system configurations while considering feasible proposed control logics. Configuration 1 integrates a separate hot water tank and a refrigerant-to-water heat exchanger (HEX), also known as a Hydro Kit while Configuration 2 incorporates a refrigerant-wrapped hot water tank. To facilitate this analysis, we developed high-fidelity system models for both configurations in Modelica, capturing system dynamics and detailed control sequences effectively. These system models were built upon the TIL library for HVAC equipment components and the Buildings library for residential building thermal load calculations. The validation of the simulation testbed utilized data from experiments conducted in the PNNL lab home for Configuration 1. To establish the simulation testbed for Configuration 2, we extended the modeling setup derived from Configuration 1. This extension specifically involved substituting the separate hot water tank and Hydro Kit with a refrigerant-wrapped hot water tank of similar sizing sourced from an actual product. The simulation analysis of heating-only and heat recovery modes reveals that Configuration 2 not only saves energy and maintains warmer tank temperatures but also demonstrates faster water heating capabilities. This is attributed to decreased energy loss and improved heat transfer. The study encompasses a wide range of scenarios, considering diverse thermal loads and water usage patterns across heating and heat recovery modes. Overall, the comprehensive results indicate that Configuration 2 achieves energy savings ranging from 3.5% to 12.2% compared to Configuration 1, depending on factors such as water usage patterns, thermal loads, and operational modes.

Configuration, Comparison, Multi-functional, Resid↗
DOE OSTI2020

Dynamic System Scaling Applied to Zr-4 Cladding under RIA Conditions

The research and development lifecycle for new fuel designs currently has an ideal 20-25 year timeline. Efforts are currrently underway to accelerate fuel design and development using high performance fuel modeling codes and reduced scale experiments with new instrumentation techniques. However current tools available require a full scale prototype to be designed and tested for fuel qualification. The thermal-hydraulics community has leveraged scaling methodologies to use reduced scale integral effect test facilities (Westinghouse AP600/1000, NuScale Power Module) in lieu of building full scale prototypes for reactor design certification. Dynamic System Scaling (DSS) is a recent development to scaling methodologies that enable the tracking and quantification of dynamic scaling distortions experienced throughout a transient. Recent TREAT experiments performed reactivity initiated accident (RIA) pulses on UO2 fuel rodlets in Zr-4 cladding and were accompanied by BISON predictions for the cladding temperature. DSS is applied to pyrometer data of outer cladding temperatures and two BISON predictions after peak cladding temperature has been reached. One BISON case uses a constant gap conductance value between the fuel and cladding and the other using a conventional gap conductance model. Results from the DSS analysis show that there is good agreement between both BISON predictions and the experimental data and that there is not a significant distortion seen between using either gap conductance model.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Plastic additives in the ocean: Use of a comprehensive dataset for meta-analysis and method development

In excess of 13,000 chemicals are added to plastics (‘additives’) to improve performance, durability, and production of plastic products. They are categorized into numerous chemical classes including flame retardants, light stabilizers, antioxidants, and plasticizers. While research on plastic additives in the marine environment has increased over the past decade, there is a lack of methodological standardization. To direct future measurement of plastic additives, we compiled a first-of-its-kind dataset of literature assessing plastic additives in marine environments, delineated by sample type (plastic debris, seawater, sediment, biota). Using this dataset, we performed a meta-analysis to summarize the state of the science. Currently, our dataset includes 217 publications published between 1978 and May 2023. The majority of publications analyzed plastic additives in biota collected from Europe and Asia. Analyses concentrated on plasticizers, brominated flame retardants, and bisphenols. Common sample preparation techniques included Solvent - Agitation extraction for plastic, sediment, and biota samples, and Solid Phase Extraction for seawater samples with dichloromethane and solvent mixtures including dichloromethane as the organic extraction solvent. Finally, most analyses were performed utilizing gas chromatography/mass spectrometry. There are a variety of data gaps illuminated by this meta-analysis, most notably the small number of compounds that have been targeted for detection compared to the large number of additives used in plastic production. The provided dataset facilitates future investigation of trends in plastic additive concentration data in the marine environment (allowing for comparison to toxicity thresholds) and acts as a starting point for optimizing and harmonizing plastic additive analytical methods.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Survey of Cyber Risk Analysis Techniques for Use in the Nuclear Industry

Using traditional probabilistic risk analysis methods for severe accident safety risk management on non-digital systems, structures, and components at nuclear power plants is well-established. In contrast, cyber risk analysis of digital assets is still an immature field with unproven techniques due, in part, to the continuously changing threat environment and the challenge of digital assets failing in unexpected ways. As the nuclear fleet continues to adopt digital instrumentation and control systems, it is increasingly important to have effective and efficient cyber risk analysis techniques to support risk management decisions, such as risk elimination by system redesign or risk mitigation by implementation of prioritized security controls. To understand the state of the art in cyber risk analysis for future research, we surveyed 36 publications across ten application domains. We describe our survey methodology and rate each technique based upon scope, adoptability, and repeatability. In this work, we examine the unique constraints of the nuclear industry and outline the strengths and weaknesses of using the cyber risk analysis techniques in the industry, highlighting gaps with current techniques. We also discuss challenges and potential research directions for advancing the science for both existing and new advanced reactors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Technology Demonstration of a High-Pressure Swirl Oxy-Coal Combustor

This technical report presents the exploration of the design and prototyping of a High-Pressure Swirl Oxy-coal Combustor. Pressurized oxy-coal combustion systems have the potential to improve efficiency along with an increased carbon capture rate. Reduction of flue gas at higher pressure, smaller system size, and capital cost reductions render high-pressure oxy-coal systems particularly attractive as next-generation energy-producing systems. High-pressure oxy-coal combustion systems are a recent concept, and thus operability issues of combustor designs for such systems are not fully understood. Significant challenges exist to maintain oxy-coal combustion stability at elevated pressure and a high CO 2 diluent environment. Although a body of knowledge exists for high-pressure oxygen combustion in rocket engines (or similar applications), it is yet to be strategized how these fundamental concepts can be translated to low-temperature CO 2 diluent combustion regimes. The realization of the pressurized oxy-coal based systems requires combustor components to be designed and demonstrated for an operating pressure over 10 bar. However, pressurized oxy-coal combustor design information at this pressure range and scale relevant to validate those proposed systems is currently limited. Experimental data from MWth scale oxy-coal combustors are needed to identify the optimal trade-off between net efficiency and systems size. The proposed effort is aimed at demonstrating a 1 MWth down-fired swirl Oxy-Coal combustor and investigate the interrelation between combustor operating conditions (pressure; flame stability; flue gas recirculation ratio) and conversion efficiencies to minimize oxygen requirements. One of the key challenges is to configure burner design (i.e., swirl number and injector) and operating conditions for high-pressure oxy-coal combustion systems. These experiments differ from current systems partly due to the high theoretical flame temperature and related burner operability issues associated with oxy-combustion. An ASPEN PLUS® model study for 550 MWe TIPS and ENEL pressurized oxy-coal systems with CO 2 recirculation was performed to evaluate system design, subsystems sizing, and operating condition determination. The system analysis effort included TRL and technology gap determination of subsystems and critical components. This information was scaled to develop design requirements (design pressure and flue gas recirculation: RR Flue Gas = $\frac{m_{flue}}{m_{total}}$) for the 1 MWth combustor. The effects of a wide range of carbon dioxide recirculation ratios on the thermal efficiency of ENEL and TIPS cycles are studied. The pressure of 10 bar and 80 bar are used for ENEL and TIPS cycles, respectively. The thermal efficiency of ENEL is significantly higher than the efficiency of TIPS at a pressure of less than 10 bar. The insights from system analysis were then used to design a 1 MWth swirl oxy-coal combustor. Flame temperature analysis and material strength analysis was performed to determine the combustor thickness. The structural integrity of the combustor was validated by finite element analysis using Abacus® and Hypermesh®. Feasibility of igniters and secondary burners are investigated in successful high-pressure oxy-methane combustion. The secondary burners are designed in such a way that it can operate between 100 to 500 kW firing input. Three generations of the pintle injector were designed based on swirl numbers (S=0, 0.9, and 1.2). Key pintle injector parameters such as pintle size, pintle orifice size, spray pattern were investigated by cold flow tests. Information from these tests was used to modify injector design for smooth and successful operation. A 5 mm pintle orifice size was decided upon as the optimum size for oxy-coal operation for the combustor. Shadow sizing experiments were performed to identify the atomization rate of each injector. Different coal water slurry mixtures (30 – 50% coal by wt% in the mixture) at various total momentum ratios (TMR) were investigated for this purpose. These experiments provided decisive information to choose the best design of the injector. The injector with 1.2 swirl provided higher atomization in all cases than other designs. The mean equivalent droplet size of the jet was similar at different TMR and mixture ratios using this injector, thus making it suitable for use in most cases. Therefore, the 1.2 swirl-pintle injector was chosen for the shakedown test. The combustor and other sub-systems, including feed systems and control and data acquisition, have been manufactured, assembled, and integrated. The total system integration and installation began on July 1, 2020. The shake-down tests and initial operational capability demonstration are expected to be completed by September 30, 2020.

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS2023

An Enabling Platform for Achieving Multiscale Multiphysics Analysis of Multiphase Materials

This paper will address current NASA GRC research efforts utilizing the NASA Multiscale Analysis Tool (NASMAT) which address technical gaps in three of the Vision 2040 key discipline areas. NASMAT is a versatile platform for performing computationally efficient multiscale analyses of heterogeneous materials and is available free through the NASA software catalog. It offers the user flexibility to define an arbitrary number of length scales (levels) where a variety of micromechanics theories can be implemented at each level. Micromechanics theories can be selected to balance accuracy and computational efficiency and range from analytical (Mori-Tanaka) to several semi-analytical (method of cells) formulations. The resulting anisotropic, evolving nonlinear, thermomechanical constitutive model can also be coupled with external software and used to perform multiscale analyses of more complex structures. A recent application to model a complex, three-dimensional woven composite, with a particular emphasis placed on multiscale measurements utilized to enhance the quality of the multiscale analysis will be discussed. Since typical NASMAT analyses can be completed on the order of seconds to minutes, a second example will demonstrate the ability to generate large quantities of data useful for sensitivity analysis, uncertainty quantification, or machine learning applications. Current progress on implementing NASMAT within a multiscale digital thread/digital twin framework will also be addressed. These examples will demonstrate that NASMAT is an enabling platform for achieving the goals in Vision 2040.

Multiscale↗
DOE OSTI2020

Unusual superparamagnetic behavior in bulk Ba 0.198 La 0.784 Ti 0.096 Fe 0.8 O 3-δ

Here, we report the observation of superparamgnetic behavior induced by the substitution La 3+ by Ba 2+ at A-sites and Fe +3 by Ti 4+ at B-sites. Ba 0.198 La 0.784 Ti 0.096 Fe 0.8 O 3-δ was synthesized via solid state reaction. The Rietveld refinements revealed an orthorhombic (Pbnm). The low-mag STEM results showed that the particles were found to exhibit square like shape and formed in single crystal with high degree of crystallinity. The particle size ranges of 50 300 nm. Element mapping demonstrates a complementary distribution between Ba and La, while homogenous distribution is found for Fe and O. The optical band gap determined from UV-vis analysis is equal to 1.93 eV which is smaller than the reported one for LaFeO 3 and BaTiO 3 . The hysteresis loops at 300 K and 10 K show superparamagnetic behavior, which deviate extremely from the antiferromagnetic nature of LaFeO 3 perovskite. The temperature dependent magnetization demonstrates that the material kept a net magnetization of 12.29 (emu/g) at very low temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Legacy Site 377 (Former Building 377) Soil Sampling and Analysis Plan Addendum 1 (April 2023)

The purpose of this addendum is to address data gaps identified in the Legacy Site 377 (Former Building 377) Soil Sampling and Analysis Plan (SAP) (LLNL-AM-826971) (LLNL 2021a) and the Phase II Site Assessment Report for Legacy Slab 377 (LLNL-TM-828194) (LLNL 2021b). This addendum will be used in conjunction with the 2021 SAP. All policies and procedures set forth in the SAP that are not modified in this addendum will remain in effect for the duration of the project, where applicable.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

From Intermolecular Interaction Energies and Observable Shifts to Component Contributions and Back Again: A Tale of Variational Energy Decomposition Analysis

Quantum chemistry in the form of density functional theory (DFT) calculations is a powerful numerical experiment for predicting intermolecular interaction energies. However, no chemical insight is gained in this way beyond predictions of observables. Energy decomposition analysis (EDA) can quantitatively bridge this gap by providing values for the chemical drivers of the interactions, such as permanent electrostatics, Pauli repulsion, dispersion, and charge transfer. These energetic contributions are identified by performing DFT calculations with constraints that disable components of the interaction. This review describes the second-generation version of the absolutely localized molecular orbital EDA (ALMO-EDA-II). The effects of different physical contributions on changes in observables such as structure and vibrational frequencies upon complex formation are characterized via the adiabatic EDA. Example applications include red- versus blue-shifting hydrogen bonds; the bonding and frequency shifts of CO, N 2 , and BF bound to a [Ru(II)(NH 3 ) 5 ] 2 + moiety; and the nature of the strongly bound complexes between pyridine and the benzene and naphthalene radical cations. Additionally, the use of ALMO-EDA-II to benchmark and guide the development of advanced force fields for molecular simulation is illustrated with the recent, very promising, MB-UCB potential.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Glycerol Adsorption on TiO 2 Surfaces: A Systematic Periodic DFT Study

Abstract Conversion of glycerol to added‐value products is desirable due to its surplus during biodiesel synthesis. TiO 2 has been the most explored catalyst. We performed a systematic study of glycerol adsorption on anatase (101), anatase (001), and rutile (110) TiO 2 at the Density Functional Theory level. We found several adsorption modes on these surfaces, with anatase (101) being the less reactive one, leading to adsorption energies between −0.8 and −0.4 eV, with all adsorptions molecular in nature. On the contrary, anatase (001) is the most reactive surface, leading to both molecular and dissociative adsorption modes, with energies ranging from −4 to −1 eV and undergoing severe surface reconstructions in some cases. Rutile (110) also shows both molecular and dissociative adsorptions, but it is less reactive than anatase (001). Surfaces with oxygen vacancies affects the adsorbed states and energies. The electronic structure analysis reveals that glycerol adsorption mainly affects the band gap of the material and not the individual contributions to the valence and conduction band. Bader charge analysis shows that strong adsorption modes on anatase (001) and rutile (110) are associated with large charge transfer from glycerol to the surface, while weak and molecular adsorption modes involve low charge transfer.

Chemistry↗
DOE OSTI2020

Design, Analysis, Comparison, and Experimental Validation of Insulated Metal Substrates for High-Power Wide-Bandgap Power Modules

Direct bonded copper (DBC) substrates used in power modules have limited heat spreading and manufacturing capability due to ceramic properties and manufacturing technology. The ceramic and copper bonding is also subject to high mechanical stress due to coefficient of thermal expansion mismatch between the copper and the ceramic. For wide-bandgap (WBG) devices, it is of interest exploring new substrate technologies that can overcome some of the challenges of direct bonded copper substrates. In this technical paper, the design, analysis, and comparison of insulated metal substrates (IMSs) for high-power wide-bandgap semiconductor-based power modules are discussed. This paper starts with technical description and discussion of state-of-the-art DBC substrates with different ceramic insulators such as aluminum nitride (AlN), Al 2 O 3 , and Si 3 N 4 . Next, an introduction of IMSs and their material properties, and a design approach for SiC (silicon carbide) metal-oxide-semiconductor field-effect transistor (MOSFET)-based power modules for high-power applications is provided. The influence of dielectric thickness on the power handling capability of the substrate are also discussed. The designed IMS and DBC substrates were characterized in terms of steady-state and transient thermal performance using finite element simulation. Finally, the performance of the IMS and DBC are validated in an experimental setup under different loading and cooling temperature conditions. We report the simulation and experimental results showed that the IMS can provide high steady-state thermal performance for high-power modules based on SiC MOSFETs. Furthermore, the IMS provided enhanced transient thermal performance, which provided a reduced junction temperature when the module is operated at low fundamental output frequencies in traction drive systems.

42 ENGINEERING↗
DOE OSTI2023

High dimensional binary classification under label shift: phase transition and regularization

Label Shift has been widely believed to be harmful to the generalization performance of machine learning models. Researchers have proposed many approaches to mitigate the impact of the label shift, e.g., balancing the training data. However, these methods often consider the underparametrized regime, where the sample size is much larger than the data dimension. The research under the overparametrized regime is very limited. Here, to bridge this gap, we propose a new asymptotic analysis of the Fisher Linear Discriminant classifier for binary classification with label shift. Specifically, we prove that there exists a phase transition phenomenon: Under certain overparametrized regime, the classifier trained using imbalanced data outperforms the counterpart with reduced balanced data. Moreover, we investigate the impact of regularization to the label shift: The aforementioned phase transition vanishes as the regularization becomes strong.

binary classification↗
DOE OSTI2020

Structural modeling and validation of laminated stacks in magnetic gearing applications

Laminated structures are commonly employed in magnetic gears based on their ability to direct magnetic flux, while inhibiting eddy currents. Unfortunately, the stiffness of the laminated structure is much lower than a solid part, which can lead to unacceptable deflections, given the large magnetic forces and small air gaps in magnetic gears. Finite element analysis of laminations to accurately predict these deflections can be computationally expensive due to the small elements needed to model the thin lamination dimensions. These analyses also have some uncertainty due to the assignment of bonding stiffness. This paper presents a means of accurately modelling the deflection of a laminated stack with reduced complexity and computational time, which is compared to experimental results. Here, the resulting methods are then used to assess the magnetic and mechanical advantages of different designs for the modulating pieces of a magnetic gear.

42 ENGINEERING↗
DOE OSTI2020

A method for mapping submicron-scale crystallographic order/disorder applied to human tooth enamel

Tooth enamel, the outermost layer of human teeth, is a complex, hierarchically structured biocomposite. The details of this structure are important in multiple human health contexts, from understanding the progression of dental caries (tooth decay) to understanding the process of amelogenesis and related developmental defects. Enamel is composed primarily of long, nanoscale crystallites of hydroxyapatite that are bundled by the thousands to form micron-scale rods. Studies with transmission electron microscopy show the relationships between small groups of crystallites and X-ray diffraction characterize averages over many rods, but the direct measurement of variations in local crystallographic structure across and between enamel rods has been missing. Here, we describe a synchrotron X-ray-based experimental approach and a novel analysis method developed to address this gap in knowledge. A ~500-nm-wide beam of monochromatic X-rays in conjunction with a sample section only 1 μm in thickness enables 2D diffraction patterns to be collected from small well-separated volumes within the enamel microstructure but still probes enough crystallites (~300 per pattern) to extract population-level statistics on crystallographic features like lattice parameter, crystallite size, and orientation distributions. Furthermore, the development of a quantitative metric to characterize relative order and disorder based on the azimuthal autocorrelation of diffracted intensity enables these crystallographic measurements to be correlated with their location within the enamel microstructure (e.g., between rod and interrod regions). These methods represent a step forward in the characterization of human enamel and will elucidate the variation of the crystallographic structure across and between enamel rods for the first time.

crystallographic order/disorder↗
DOE OSTI2023

Electromagnetic signatures of a chiral quantum spin liquid

Quantum spin liquids (QSL) have emerged as a captivating subject within interacting spin systems that exhibit no magnetic ordering even at the lowest temperature accessible experimentally. However, definitive experimental evidence remains elusive. In light of the recent surge in theoretical and experimental interest in the half-filled Hubbard model on a triangular lattice, which offers the potential for stabilizing a chiral QSL, we investigate the electromagnetic signatures of this phase to facilitate experimental detection. Utilizing a combination of parton mean-field theory and unbiased density-matrix renormalization group calculations, we systematically examine the electrical charge and orbital electrical current associated with a spinon excitation in the chiral QSL. Additionally, we calculate the longitudinal and transverse optical conductivities below the Mott gap. Furthermore, employing quantum field theory analysis, we unravel the connection between spinon excitations and emergent as well as physical gauge fields. Our results demonstrate that the chiral QSL phase exhibits a distinct electromagnetic response, even within a Mott insulator regime. This finding holds great potential for enabling the experimental detection of this long-sought-after phase.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effects of Al concentration on the structure and conductivity of lithium lanthanum zirconium oxide

Cubic Li 7-3x Al x La 3 Zr 2 O 12 (LLZO) is a promising, next-generation solid electrolyte due to its stability with Li-metal and high bulk conductivity (~1 mS cm -1 ). However, the source of the high conductivity is not completely understood. In this work, we address this key knowledge gap through the integration of elemental analysis, neutron diffraction sensitive to Li and O atoms, and impedance spectroscopy to understand the structure–property correlations for LLZO. We show the metal–oxygen framework structure remains constant with variation in Al substitution, resulting in a constant activation energy of ~0.35 eV and little effect on the bulk conductivity. Instead, Li concentration, Al blocking and trapping of mobile defects, and Li–Li nearest neighbor interactions largely control the Al substituted LLZO bulk conductivity, resulting in decreases from 0.73 to 0.22 mS cm -1 as the Al concentration increases from 0.17 to 0.32 mol. These results differ from those of Ta substituted LLZO, where the framework structure and Li–Li site distances play large roles in controlling the conductivity. The increased understanding of the controlling factors of conductivity allows for greater ability to tailor the design of and substitution into the LLZO structure for improved conductivity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗