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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Kentucky: Using LEAD Tool Data to Fund Energy Efficiency Programs

The Kentucky Office of Energy Policy (OEP) applied the U.S. Department of Energy’s (DOE’s) web-based Low-Income Energy Affordability Data (LEAD) Tool to identify areas of their state with energy affordability needs. Kentucky OEP staff used the LEAD Tool to identify counties in Kentucky with the highest energy burden, which is the percentage of household income spent on energy. With this knowledge, Kentucky OEP staff allocated funds to relevant nonprofit organizations that provide home repairs, weatherization upgrades, and other solutions in areas where these services have the highest potential energy saving benefits and can reduce energy burden.

Low-Income Energy Affordability Data Tool, LEAD To↗
DOE OSTI2023

Low-Income Energy Affordability Data (LEAD) Tool

The Low-income Energy Affordability Data (LEAD) tool was created to provide data, such as energy burden, to stakeholders to make data driven decisions. The LEAD Tool provides a starting point for local governments, NGOs, companies, etc. to find areas with higher energy burden and cost to inform decisions about funding distribution and program qualifications. This presentation was given to energy efficiency and conservation block grant program applicants to explain how this tool can help them develop their energy efficiency and conservation strategy.

ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2025

Pressure‐Induced Structural and Optoelectronic Modulations in 2D Dion‐Jacobson Hybrid Lead Iodide Perovskites With a Rigid Spacer

2D hybrid organic-inorganic perovskites (HOIPs) are known for their superior chemical and thermal stability over 3D variants, positioning them as promising materials for advanced optoelectronic applications. Applying external high pressure is an effective strategy to modify their structures and tune their optoelectronic properties. This study examines the high-pressure behavior of a Dion-Jacobson type 2D HOIP, DPDAPbI 4 , which incorporates the rigid organic spacer N,N-dimethylphenylene-p-diammonium (DPDA). Utilizing photoluminescence, UV–visible absorption, vibrational spectroscopy, and in situ synchrotron powder X-ray diffraction, an isostructural phase transition is identified near 1.5 GPa, marked by a notable shift in photoluminescence intensity linked to free exciton emission. Synchrotron X-ray diffraction reveals significant anisotropic compression along the c-axis, while structural analysis indicates the rare phenomenon of reduced lead-iodide octahedral distortion below 2 GPa, contrasting with the increased octahedral distortion reported in most previous studies on lead-based 2D HOIPs. Density functional theory calculations elucidate the structural origins and mechanisms driving the pressure-induced phase transition and optoelectronic tuning. These findings underscore the critical interplay between rigid organic spacers and inorganic octahedra in modulating high-pressure optoelectronic properties, offering valuable insights for designing future 2D HOIPs with tailored functionalities.

14 SOLAR ENERGY↗
DOE OSTI2022

Cesium Lead Halide Perovskite Nanocrystals Assembled in Metal–Organic Frameworks for Stable Blue Light Emitting Diodes

All inorganic cesium lead trihalide nanocrystals are promising light emitters for bright light emitting diodes (LEDs). Here we demonstrate CsPb(BrCl) 1.5 nanocrystals in metal-organic frameworks (MOF) thin films to achieve bright and stable blue LEDs. The lead metal nodes in the MOF thin film react with Cs-halide salts, resulting in 10~20 nm nanocrystals. This is revealed by X-ray scattering and transmission electron microscopy. Employing the CsPbX 3 - MOF thin films as emission layers, bright deep blue and sky-blue LEDs are demonstrated that emit at 452 nm and 476 nm respectively. The maximum external quantum efficiencies of these devices are 0.72% for deep blue LEDs and 5.6% for sky blue LEDs. More importantly, the device can maintain 50% of its original electroluminescence (T 50 ) for 2.23 hours when driving at 4.2V. Detailed optical spectroscopy and time-of-flight secondary ion mass spectroscopy suggest that the ion migration can be suppressed that maintains the emission brightness and spectra. Our study provides a new route for fabricating stable blue light emitting diodes with all-inorganic perovskite nanocrystals.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Synthesis and Characterization of a New Ferroelectric with Low Lead Content, a High Curie Temperature, and a High Piezoelectric Response

Abstract A new solid solution (1− x )Bi(Fe 2/8 Ti 3/8 Mg 3/8 )O 3 –( x )PbTiO 3 (BFTM‐PT) is synthesized and the electromechanical properties are measured. This system is defined as a low‐lead material with ferroelectric/piezoelectric behavior and a morphotropic phase boundary (MPB) that leads to enhanced properties. The MPB is located between x = 0.30 and 0.35 and coincides with a structural phase transition and a sharp increase in the piezoelectric response. The system demonstrates ferroelectric hysteresis where x = 0.325 displays the best properties with a maximum polarization of 39 µC cm −2 and a remnant polarization of 26 µC cm −2 . The range of compositions has high Curie temperature ( T c ), ranging from 625–650 °C. Materials with a T c above 400 °C typically have a low d 33 of <50 pC N −1 at room temperature. However, BFTM‐PT has a higher d 33 that most other compositions with a T c in this range, with the highest being 145 pC N −1 for x = 0.375. The d 33 drops off above 100 °C, but doping studies can be done in the future to stabilize the piezoelectric response at higher temperatures. These outstanding properties open the possibility of new transducer applications, in particular ones requiring high temperature and high power.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Light–Induced Frenkel Defect Pair Formation Can Lead to Phase–Segregation of Otherwise Miscible Halide Perovskite Alloys

Alloys of ABX 3 halide perovskites (HP) exhibit unique phase behavior compared to traditional III-V and II-VI semiconductor alloys used in solar cells. While the latter typically have good mutual miscibility when their mixed components are size matched, and phase-segregate when size mismatched, HP alloys show good miscibility in the dark but can phase-segregate under light. Quantum mechanical calculations described herein reveal light-induced defect formation and migration hold the key. Specifically, the interaction between a halogen vacancy V X with halogen interstitial X i forming together a Frenkel-pair defect emerges as the enabler for phase-segregation in HP alloys. At a threshold bromine composition in the Br-I alloys, the photogenerated holes in the valence band localize, creating thereby a doubly-charged iodine Frenkel-pair (V I + I i ) 2+ . Faster migration of iodine over bromine interstitial into the vacant iodine V I site leads to the formation of iodine-rich and iodine-depleted regions, establishing phase-segregation. Removal of the mobile defects–the agent of segregation–by dark thermal annealing, supplies the opposing force, leading to reversal of phase-segregation. Furthermore, this atomistic understanding can enable some control of the phase-segregation by selecting substituting elements on the B site–such as replacing some Pb by Sn–that are unable to form stable Frenkel defects.

14 SOLAR ENERGY↗
DOE OSTI2025

Computational and Experimental Investigation of Chiral and Achiral Two‐Dimensional Organic Lead Bromide Perovskites: Octahedral Distortions and Electronic and Optical Properties

A computational investigation is presented, in conjunction with synthesis and experimental characterization, into the structural, electronic, and optical properties of layered two-dimensional organic lead bromide perovskites. Materials based on the chiral (R/S)-4-fluoro-α-methylbenzylammonium (R/S-FMBA), which have been shown to lead to bright room-temperature circularly polarized luminescence, are contrasted with the similar achiral 4-fluorobenzylammonium (FBA). Using density functional theory (DFT) with van der Waals (vdW) corrections, relaxed structures (compared with X-ray diffraction, XRD) and optical absorption spectra (compared with experiments) are studied, as well as band structure and orbital character of transitions. A Python code is developed and provided to calculate octahedral distortions and compare DFT and XRD results, finding that vdW corrections are important for accuracy and that DFT overestimates octahedral tilt angles. (FMBA) 2 PbBr 4 shows among the largest tilt angle differences (often termed Δ β ) reported, 14°–15°, indicating strong inversion symmetry-breaking, which enables its chiral emission. A large resulting Dresselhaus spin-splitting effect is found. The lowest-energy optical transitions involve the perovskite only and are polarized within the layer. This work furthers understanding of structure-property relations with applications to optoelectronics and spintronics.

UV/vis spectroscopy↗
DOE OSTI2024

High‐throughput combinatorial approach expedites the synthesis of a lead‐free relaxor ferroelectric system

Abstract Developing novel lead‐free ferroelectric materials is crucial for next‐generation microelectronic technologies that are energy efficient and environment friendly. However, materials discovery and property optimization are typically time‐consuming due to the limited throughput of traditional synthesis methods. In this work, we use a high‐throughput combinatorial synthesis approach to fabricate lead‐free ferroelectric superlattices and solid solutions of (Ba 0.7 Ca 0.3 )TiO 3 (BCT) and Ba(Zr 0.2 Ti 0.8 )O 3 (BZT) phases with continuous variation of composition and layer thickness. High‐resolution x‐ray diffraction (XRD) and analytical scanning transmission electron microscopy (STEM) demonstrate high film quality and well‐controlled compositional gradients. Ferroelectric and dielectric property measurements identify the “optimal property point” achieved at the composition of 48BZT–52BCT. Displacement vector maps reveal that ferroelectric domain sizes are tunable by varying {BCT–BZT} N superlattice geometry. This high‐throughput synthesis approach can be applied to many other material systems to expedite new materials discovery and properties optimization, allowing for the exploration of a large area of phase space within a single growth. image

36 MATERIALS SCIENCE↗
DOE OSTI2025

Strontium‐Enriched Barite for Enhanced PbSO 4 Nucleation in Lead‐Acid Batteries

Abstract Barite (BaSO 4 ) crystals are an important additive in lead acid batteries due to their ability to promote the controlled nucleation and growth of anglesite (PbSO 4 ) during battery cycling. This is due to BaSO 4 ’s isostructural match with PbSO 4 , which facilitates epitaxial nucleation. However, BaSO 4 ’s efficacy as a nucleation promoter is limited by lattice mismatches between the two phases of 1–5%. Here, strontium‐enriched barite, (Ba,Sr)SO 4 , is synthesized to produce a nucleating promoter that displays an improved lattice match with PbSO 4 . Nucleation of PbSO 4 from Pb‐rich sulfuric acid solutions on strontium‐free and strontium‐enriched barite (up to 17 mol% Sr) is investigated using in‐situ atomic force microscopy and optical microscopy. At low strontium concentrations, PbSO 4 forms by the Stranski–Krastanov growth pathway (monolayer + island formation), with most nucleation occurring on edges and surface defects. At higher concentrations, the layer‐by‐layer growth mechanism known as Frank van‐der‐Merwe growth is observed, which allows for facile growth of continuous PbSO 4 films across the BaSO 4 surface. These films are successfully re‐dissolved on exposure to Pb‐free sulfuric acid. The results show that strontium incorporation fundamentally alters the mechanism of PbSO 4 nucleation on BaSO 4 , and thus provides a potential avenue for creating improved nucleation promoters in lead‐acid batteries.

Campbell, Colin T. [Pacific Northwest National Lab↗
DOE OSTI2022

Computational Methodology to Simulate Pyrometallurgical Processes in a Secondary Lead Furnace

Pyrometallurgical recovery of nonferrous metals involves a combination of thermally intensive transformations during exothermic gas-phase reactions, endothermic decomposition of solid charge, and melting of simpler solids. In the recovery of secondary lead, simultaneous thermal effects in a reverberatory-style furnace cause a melt pool to accumulate at the bottom, with lighter solids (slag) floating above and gaseous products from decomposition of the charge diffusing through the gas–slag interface. Species from oxy-fuel combustion of natural gas, species profiles from smelting reactions, and the formation of a melt pool consisting primarily of lead are simulated via a time-averaged formulation. Predictions of outflow are compared with preset inflow profiles to ensure conservation of mass. Thermal profiles for solid, liquid, and gas phases are presented by species. A novel method is implemented to model the latent heat of fusion using a heterogeneous chemical reaction. The simulation is conducted in Simcenter STAR-CCM+ v. 16.02.009-R8.

Rao, Vivek↗
DOE OSTI2021

Sub-leading structures in superconformal indices: subdominant saddles and logarithmic contributions

We systematically study various sub-leading structures in the superconformal index of N = 4 supersymmetric Yang-Mills theory with SU(N) gauge group. We concentrate in the superconformal index description as a matrix model of elliptic gamma functions and in the Bethe-Ansatz presentation. Our saddle-point approximation goes beyond the Cardy-like limit and we uncover various saddles governed by a matrix model corresponding to SU(N) Chern-Simons theory. The dominant saddle, however, leads to perfect agreement with the Bethe-Ansatz approach. We also determine the logarithmic correction to the superconformal index to be log N, finding precise agreement between the saddle-point and Bethe-Ansatz approaches in their respective approximations. We generalize the two approaches to cover a large class of 4d N = 1 superconformal theories. We find that also in this case both approximations agree all the way down to a universal contribution of the form log N. The universality of this last result constitutes a robust signature of this ultraviolet description of asymptotically AdS 5 black holes and could be tested by low-energy IIB supergravity.

1/N expansion↗
DOE OSTI2025

e + e – → ZH process in the SMEFT beyond leading order

We systematically study potential effects of Beyond the Standard Model physics in the e + e – → ZH process. To this end, we include all relevant dimension-6 Standard Model Effective Field Theory operators and work to next-to-leading order (NLO) accuracy in the electroweak coupling. We consider both polarized and unpolarized electron and positron beams and present results for $\sqrt {s}$ = 240, 365 and 500 GeV, emphasizing contributions where the NLO predictions differ significantly from the leading order results. At NLO, a sensitivity arises to operators that do not contribute at tree level, such as the Higgs tri-linear coupling, CP-violating operators, and dimension-6 operators involving the top quark, among many others. We compare the prospects of future e + e – colliders to explore these new physics effects with existing measurements from the LHC, electron EDMs (for CP violating operators), and Z pole measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Study of Drell-Yan dimuon production in proton-lead collisions at $\sqrt{s_\mathrm{NN}} =$ 8.16 TeV

Differential cross sections for the Drell-Yan process, including Z boson production, using the dimuon decay channel are measured in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of 8.16 TeV. A data sample recorded with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 173 nb$^{−1}$. The differential cross section as a function of the dimuon mass is measured in the range 15–600 GeV, for the first time in proton-nucleus collisions. It is also reported as a function of dimuon rapidity over the mass ranges 15–60 GeV and 60–120 GeV, and ratios for the p-going over the Pb-going beam directions are built. In both mass ranges, the differential cross sections as functions of the dimuon transverse momentum p$_{T}$ and of a geometric variable ϕ$^{*}$ are measured, where ϕ$^{*}$ highly correlates with p$_{T}$ but is determined with higher precision. In the Z mass region, the rapidity dependence of the data indicate a modification of the distribution of partons within a lead nucleus as compared to the proton case. The data are more precise than predictions based upon current models of parton distributions.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

The sub-leading scattering waveform from amplitudes

We compute the next-to-leading order term in the scattering waveform of uncharged black holes in classical general relativity and of half-BPS black holes in $\mathcal{N}$ = 8 supergravity. We propose criteria, generalizing explicit calculations at next-to-leading or der, for determining the terms in amplitudes that contribute to local observables. For general relativity, we construct the relevant classical integrand through generalized unitary in two distinct ways, (1) in a heavy-particle effective theory and (2) in general relativity minimally-coupled to scalar fields. With a suitable prescription for the matter propagator in the former, we find agreement between the two methods, thus demonstrating the absence of interference of quantum and classically-singular contributions. The classical $\mathcal{N}$ = 8 integrand for massive scalar fields is constructed through dimensional reduction of the known five-point one-loop integrand. Our calculation exhibits novel features compared to conservative calculations and inclusive observables, such as the appearance of master integrals with intersecting matter lines and the appearance of a classical infrared divergence whose absence from classical observables requires a suitable definition of the retarded time.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Leading-color two-loop QCD corrections for three-jet production at hadron colliders

We present the complete set of leading-color two-loop contributions required to obtain next-to-next-to-leading-order (NNLO) QCD corrections to three-jet production at hadron colliders. We obtain analytic expressions for a generating set of finite remainders, valid in the physical region for three-jet production. The analytic continuation of the known Euclidean-region results is determined from a small set of numerical evaluations of the amplitudes. We obtain analytic expressions that are suitable for phenomenological applications and we present a C++ library for their efficient and stable numerical evaluation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Next-to-leading power endpoint factorization and resummation for off-diagonal “gluon” thrust

The lack of convergence of the convolution integrals appearing in next-to-leading-power (NLP) factorization theorems prevents the applications of existing methods to resum power-suppressed large logarithmic corrections in collider physics. We consider thrust distribution in the two-jet region for the flavour-nonsinglet off-diagonal contribution, where a gluon-initiated jet recoils against a quark-antiquark pair, which is power-suppressed. With the help of operatorial endpoint factorization conditions, we obtain a factorization formula, where the individual terms are free from endpoint divergences in convolutions and can be expressed in terms of renormalized hard, soft and collinear functions in four dimensions. This allows us to perform the first resummation of the endpoint-divergent SCETI observables at the leading logarithmic accuracy using exclusively renormalization-group methods. The presented approach relies on universal properties of the soft and collinear limits and may serve as a paradigm for the systematic NLP resummation for other 1 → 2 and 2 → 1 collider physics processes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Suppression of diffraction in deep-inelastic scattering on nuclei and dynamical mechanism of leading twist nuclear shadowing

Abstract Using the leading twist approach (LTA) to nuclear shadowing, we calculate the ratios of diffractive and usual parton distributions for a heavy nucleus (Pb) and the proton,$$ {R}_{A/p}=\left({f}_{i/A}^{D(3)}/{f}_{i/A}\right)/\left({f}_{i/p}^{D(3)}/{f}_{i/p}\right) $$ R A / p = f i / A D 3 / f i / A / f i / p D 3 / f i / p , for coherent and summed (coherent plus quasi-elastic) nuclear deep-inelastic scattering. We find thatR A/p ≈ 0.5 − 1 for quarks as well as for the ratio of the diffractive and total cross sections$$ {\left[\left({d\sigma}_{\textrm{diff}}/{d M}_X^2\right)/{\sigma}_{\textrm{tot}}\right]}_{eA}/{\left[\left({d\sigma}_{\textrm{diff}}/{d M}_X^2\right)/{\sigma}_{\textrm{tot}}\right]}_{ep} $$ dσ diff / dM X 2 / σ tot eA / dσ diff / dM X 2 / σ tot ep andR A/p ≈ 0.5 − 1.3 for gluons in a broad range ofx, including the kinematics of the Electron-Ion Collider, which reaffirms the difference from the nuclear enhancement ofR A/p predicted in the gluon saturation framework. We demonstrate that the magnitude ofR A/p is controlled by the cross section of the interaction of hadronic fluctuations of the virtual photon with target nucleons, which explains an enhancement ofR A/p in the color dipole model and its suppression in LTA. We argue that the black disk limit corresponds toR A/p = 1 and$$ {R}_{A/p}^{\textrm{coh}} $$ R A / p coh = 0.86 for the summed and coherent scattering, respectively. Relying on an intuitive definition of the saturation scale, we show that the ratio of the saturation scales of a heavy nucleus and proton$$ {Q}_{sA}^2(b)/{Q}_{sp}^2(b)\approx 1 $$ Q sA 2 b / Q sp 2 b ≈ 1 at small impact parametersbdue to the strong leading twist nuclear shadowing and diluteness of the nuclear density.

Physics↗
DOE OSTI2022

The analytic two-loop soft function for leading-jet p T

We present the calculation of the two-loop soft function for the transverse momentum distribution of the leading jet produced in association with any colour-singlet system (e.g. a Higgs or a Z boson). This constitutes a central ingredient for the resummation of the above distribution as well as the jet-vetoed cross section at the next-to-next-to-next-to-leading logarithmic order, both of which play an important role in the precision physics programme at the Large Hadron Collider. The calculation is performed in soft-collinear effective theory with an appropriate regularisation of the rapidity divergences that occur in the phase-space integrals. We obtain analytic results by employing an exponential regulator and by taking a Laurent expansion in the jet radius R . All expressions are presented as supplementary material attached to this article.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗