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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Phase Equilibria in the ZnO-“FeO”-SiO{sub 2} System in Reducing Atmosphere and in the ZnO-“FeO”-SiO{sub 2}-“Cu{sub 2}O” System in Equilibrium with Liquid Copper Metal at 1250 °C (1523 K)

Recent experimental studies in the ZnO-“FeO”-SiO{sub 2} system in reducing atmosphere demonstrated significant discrepancies with the current FactSage thermodynamic model developed using previous experimental data in this system in equilibrium with metallic iron and air. The present experimental study on phase equilibria in the ZnO-“FeO”-SiO{sub 2}-“Cu{sub 2}O” system in equilibrium with liquid copper at 1250 °C (1523 K) at low copper oxide concentrations in slag was initiated and undertaken to resolve these discrepancies. A high-temperature equilibration–rapid quenching–electron-probe X-ray microanalysis (EPMA) technique using a primary phase substrate support and closed system approach with Cu metal introduced to determine effective equilibrium oxygen partial pressure from the Cu{sub metal}/Cu{sub 2}O{sub slag} equilibria was applied to provide accurate information on the liquidus and corresponding solid compositions in the spinel, willemite, and tridymite primary phase fields. The present results confirmed the accuracy of the FactSage model, resolved discrepancies, and demonstrated significant uncertainties in the recent studies by other authors on the system in the open reducing atmosphere. The present study shows how this closed system approach can be used to obtain key thermodynamic data on phase equilibria in systems containing volatile metal species, overcoming the limitations and uncertainties encountered in conventional open gas/condensed phase equilibration with these systems. The study highlights the importance of the focus on obtaining accurate experimental data and the risks of misleading information from inadequate experimental control and analysis. The study also demonstrates that continuing in-depth critical review and analysis of the elemental reactions taking place in complex systems is an essential step in phase equilibrium research.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Femtosecond diffraction studies of the sodium chloride phase diagram under laser shock compression

The phase diagram of sodium chloride (NaCl) under laser shock compression has been studied at Linac Coherent Light Source (LCLS) at the x-ray free-electron laser facility. Both solid–solid (B1 → B2) and solid–liquid (B2 → liquid) transitions have been observed along the Hugoniot over nanosecond time scales. By combining structural measurements through in situ x-ray diffraction, pressure determination through velocimetry, and a thermal equation-of-state, the shock-compressed data are used to constrain the phase diagram of NaCl. Transformation into the B2 phase is found to occur at 28(2) GPa, and B2–liquid coexistence is observed between 54(4) and 66(6) GPa, with near full melt at 66(6) GPa. Late-time pressure release from an initial shocked B2-state results in a B2 → B1 back transformation. Our results show agreement with previous static compression data, suggesting that the time scale for melting is very rapid and that equilibrium states in NaCl are being accessed over nanosecond time scales. Finally, a multiphase equation-of-state description of NaCl incorporated into a one-dimensional hydrocode is used to interpret pressure and temperature evolution over these rapid time scales.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Probing Ground-State Phase Transitions through Quench Dynamics

The study of quantum phase transitions requires the preparation of a many-body system near its ground state, a challenging task for many experimental systems. The measurement of quench dynamics, on the other hand, is now a routine practice in most cold atom platforms. Here we show that quintessential ingredients of quantum phase transitions can be probed directly with quench dynamics in integrable and nearly integrable systems. As a paradigmatic example, we study global quench dynamics in a transverse-field Ising model with either short-range or long-range interactions. When the model is integrable, we discover a new dynamical critical point with a nonanalytic signature in the short-range correlators. The location of the dynamical critical point matches that of the quantum critical point and can be identified using a finite-time scaling method. We extend this scaling picture to systems near integrability and demonstrate the continued existence of a dynamical critical point detectable at prethermal timescales. We quantify the difference in the locations of the dynamical and quantum critical points away from (but near) integrability. Thus, we demonstrate that this method can be used to approximately locate the quantum critical point near integrability. Furthermore, the scaling method is also relevant to experiments with finite time and system size, and our predictions are testable in near-term experiments with trapped ions and Rydberg atoms.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Study of the magnetic properties, structure, and phase transformation in the alloys of the Co-Al-W system

An experimental study of phase transformations in the system of Co-Al-W in the concentration area of the intermetallic compound Co{sub 3}(Al, W) is presented. The structure and phase composition of the Co–9 at % Al–X at % W (X = 4.5, 6.8, 8.5, 10, 12.5) alloys in depending on the tungsten content are analyzed. The Curie temperature and magnetic properties of the alloys with the different phase composition are determined.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Experimental evidence of non-equilibrium phase separation in supercritical fluids

Supercritical fluids (SCFs), widely utilized in many industries, have long been regarded as homogeneous single-phase media. Recent simulation studies identified different phases (more gas-like or liquid-like) in SCFs at equilibrium, expanding the previous notion but still not addressing non-equilibrium properties of SCFs. Here we reveal the existence of long-lived liquid-like clusters in non-equilibrium SCFs by time-resolved small-angle neutron scattering measurements. Since SCFs in industrial applications frequently operate under dynamic, non-equilibrium conditions rather than strict thermodynamic equilibrium, our findings offer crucial information for improving the use of SCFs in industrial settings, like semiconductor cleaning and plant thermal-hydraulic engineering.

Lee, Juho [Pohang Univ. of Science and Technology ↗
DOE OSTI2014

Electronic structure of Fe{sub 3}Si on Si(100) substrates

The improved performance of large-scale integrated circuits (LSIs) by the shrinking of devices is becoming difficult due to physical limitations. Here we report, the growth and formation of Fe{sub 3}Si on Si(100) and characterized by x-ray photoemission, UV photoemission and low energy electron diffraction to study the electronic structure. The results revealed that the DO{sub 3} phase formation is exist and photoemission results also support the electron diffraction outcome.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Truncation effects in the charge representation of the O(2) model

The O(2) model in Euclidean space-time is the zero-gauge-coupling limit of the compact scalar quantum electrodynamics. In this work, we obtain a dual representation of it called the charge representation. We study the quantum phase transition in the charge representation with a truncation to “spin $\textit{S}$," where the quantum numbers have an absolute value less than or equal to $\textit{S}$. The charge representation preserves the gapless-to-gapped phase transition even for the smallest spin truncation $\textit{S}$ = 1. The phase transition for $\textit{S}$ = 1 is an infinite-order Gaussian transition with the same critical exponents $\textit{δ}$ and $\textit{η}$ as the Berezinskii-Kosterlitz-Thouless (BKT) transition, while there are true BKT transitions for $\textit{S}$ ≥ 2 . The essential singularity in the correlation length for $\textit{S}$ = 1 is different from that for $\textit{S}$ ≥ 2 . The exponential convergence of the phase-transition point is studied in both Lagrangian and Hamiltonian formulations. We discuss the effects of replacing the truncated $\hat{U}^±$ = exp ($± i\hat{θ}$) operators by the spin ladder operators $\hat{S}^±$ in the Hamiltonian. The marginal operators vanish at the Gaussian transition point for $\textit{S}$ = 1, which allows us to extract the $\textit{η}$ exponent with high accuracy.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Power Supply Options for the Marpi Landfill, Saipan: Addendum to 2023 Feasibility Study

The Marpi Landfill (Marpi or the landfill), located on the northern end of the island of Saipan in the Commonwealth of the Northern Mariana Islands (CNMI), is powered by an on-site diesel generator that only operates when the landfill is open and staffed. The CNMI Office of Planning and Development (OPD) aspires to provide the Marpi Landfill with 24-hour power availability despite its remote location and to increase sustainable energy consumption within the CNMI. Pacific Northwest National Laboratory (PNNL) authored a feasibility study in 2023 that explores alternative power supply options for the landfill. This feasibility study (hereafter referred to as Phase I of this study) culminated in a report named “Power Supply Options for the Marpi Landfill, Saipan.” In Phase I, the project team investigated and prioritized seven different power supply scenarios (Table ES-1) for the landfill according to Solid Waste (SW) Taskforce priorities. The project team found that Scenario 4 (100 kW of solar photovoltaic [PV] generation, a 75 kW/300 kWh battery energy storage system [BESS], and 160 kW of diesel generation) ranked highest. Following the Phase I feasibility study, the SW Taskforce secured additional funding for PNNL to assess additional considerations regarding power supply options for Marpi. The purpose of Phase II of this study is to investigate these additional considerations, as compiled in this addendum. Some of the findings compiled here replace findings from the original report. The project team evaluated additional considerations regarding power supply options for the landfill, including modified operations to account for 24/7 power supply, electrified landfill equipment, new and replacement distribution line costs, and the social cost of carbon.

14 SOLAR ENERGY↗
DOE OSTI2019

Effect of Heating Rate during Continuous Annealing on Microstructure and Mechanical Properties of High-Strength Dual-Phase Steel

The study concerns the influence of heating rate during continuous annealing on microstructure and mechanical properties of high-strength ferrite–martensite dual-phase (DP) steel. The study suggests that the superheat (ΔT), carbon diffusion and distribution were strongly influenced by increasing the heating rate, leading to different microstructure and mechanical properties of DP steel. The morphology of martensite was observed to shift from network along ferrite grain boundaries to banded structure to uniformly dispersed, and the average ferrite grain size was refined from 5.3 to 2.0 µm. When the heating rate was 300 °C/s, the steel exhibited excellent mechanical properties with tensile strength (UTS) of 982 MPa, total elongation (TEL) of 17.5%, strength–elongation balance (UTS × TEL) of 17.2 GPa%, because of finer microstructure, uniform martensite distribution and low carbon content of martensite. Moreover, the precipitation strengthening effect of NbC is an important reason for the high-strength DP steels. In addition, the variation in strain-hardening behavior and fracture mechanism of steel subjected to different heating rates is discussed in relation to the microstructure.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of the volume fraction gradient on the phase interaction force model for disperse two-phase flows

In this work, the effects of the particle volume fraction gradient on fluid-particle interactions are studied. The phase interaction force is decomposed into three terms. For the first term, namely the symmetrized force density, we present theoretical reasoning and numerical evidence to assume that it is independent of the particle volume fraction gradient. The second term is the particle volume fraction gradient times a newly introduced diffusion stress. The third term is the divergence of the particle-fluid-particle (PFP) stress. If this assumption of independence of the particle volume fraction gradient for the first term can be verified, to the first order of the ratio of the mean distance between particles to the macroscopic lengthscale, all three terms can be studied and modeled in flows with uniform particle distributions. Models thus obtained are applicable to statistically inhomogeneous flows, with the second and third terms accounting for statistical inhomogeneity. To verify this assumption, numerical simulations of flows passing fixed arrays of particles are performed. Both uniform and nonuniform particle volume fractions are studied and compared for disperse multiphase flows with the particle Reynolds numbers ranging from 1 to 100, and particle volume fraction ranging from 1% to 26% in statistically steady states. It is found that the symmetrized force (first) term can be well approximated by the drag force obtained from studies of uniform flows. The diffusion stress is positive along the flow direction and negative in the directions perpendicular to the flow. In the case of moving particles, this stress could potentially cause particle aggregation in the flow direction and dispersion in the directions perpendicular to the flow. Finally, the diffusion stress is only important when there is a volume fraction gradient, while the PFP stress can be important in inhomogeneous flows with either nonuniform particle concentrations or nonuniform average relative velocities between the phases.

42 ENGINEERING↗
DOE OSTI2021

Hadronic resonance production and interaction in p-Pb collisions at LHC energies in EPOS3

Using the EPOS3 model with the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model to describe the hadronic phase, we study the production of short-lived hadronic resonances and the modification of their yields and p T spectra in p-Pb collisions at √sNN= 5.02 TeV. High-multiplicity p-Pb collisions exhibit similar behavior to midperipheral Pb-Pb collisions at LHC energies, and we find indications of a short-lived hadronic phase in p-Pb collisions that can modify resonance yields and p T spectra through scattering processes. The evolution of resonance production is investigated as a function of the system size, which is related to the lifetime of the hadronic phase in order to study the onset and evolution of scattering effects in p-Pb collisions. We also study hadron production separately in the core and corona parts of these collisions and explore how this division affects the total particle yields as the system size increases.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Transformation pathway from alpha to omega and texture evolution in Zr via high-pressure torsion

Using high energy X-ray diffraction, we study the phase transition from α to ω in Zr via high-pressure torsion. In this study, we examine the evolution of the texture and establish the crystallographic orientation relationship between the α and ω phases. The orientation relationship supports the Silcock/Rabinkim direct transformation pathway and excludes the possibility of transition through the intermediate β phase, the Usikov/Zilbershtein pathway. Finally, the texture development in both α and ω phases of Zr during high-pressure torsion is quantified and explained in terms of the dominant slip system and the orientation relationship during martensitic transformation.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Cs is one of the more problematic fission product radionuclides to immobilize due to its high volatility at elevated temperatures, ability to form water soluble compounds, and its mobility in many host materials. The hollandite structure is a promising crystalline host for Cs immobilization and has been traditionally fabricated by solid state sintering methods. This study presents the structure and performance of Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16}; A = Cr, Fe, Al hollandite fabricated by melt processing. Melt processing is considered advantageous given that melters are currently in use for High Level Waste (HLW) vitrification in several countries. This work details the impact of Cr additions that were demonstrated to i) promote the formation of a Cs containing hollandite phase and ii) maintain the stability of the hollandite phase in reducing conditions anticipated for multiphase waste form processing.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Asymmetric “melting” and “freezing” kinetics of the magnetostructural phase transition in B2-ordered FeRh epilayers

Synchrotron X-ray diffraction was used to study the phase transformation processes during the magnetostructural transition in a B2-ordered FeRh (001)-oriented epilayer grown on MgO by sputtering. Out-of-plane lattice constant measurements within the hysteretic regime of the transition reveal a microstructure consistent with the coexistence of lattice-expanded and contracted phases in spatially distinct regions. It was found that the phase separation is more pronounced during cooling than heating. Furthermore, whilst lattice-expanded domains that span the height of the film can be undercooled by several kelvins, there is no equivalent superheating. This asymmetry between the cooling and heating processes in FeRh is consistent with the difference in the kinetics of generic freezing and melting transitions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Phase Locking of a THz QC-VECSEL to a Microwave Reference

We report high-resolution frequency study and phase locking have been performed on a terahertz (THz) quantum-cascade vertical-external-cavity surface-emitting laser (QC-VECSEL) operating around 2.5 THz. A subharmonic diode mixer is used to down convert the THz signal to a 100 MHz intermediate frequency that is phase locked to a stable 100 MHz microwave reference. Between 90% and 95% of the QC-VECSEL signal is locked within 2 Hz of the multiplied RF reference, and amplitude fluctuations on the order of 1%–10% are observed, depending on the bias point of the QC-VECSEL. The bandwidth of the locking loop is ~1 MHz. Many noise peaks in the IF signal are observed, likely corresponding to mechanical resonances in the 10 Hz–10 kHz. These peaks are generally -30 to -60 dB below the main tone and are below the phase noise level of the multiplied RF reference that ultimately limits the phase noise of the locked QC-VECSEL.

42 ENGINEERING↗
DOE OSTI2019

Assessing liver function: diagnostic efficacy of parenchymal enhancement and liver volume ratio of Gd-EOB-DTPA-enhanced MRI study during interstitial and hepatobiliary phase

Aim: To assess the efficacy of signal intensity in interstitial and hepatobiliary phase normalized for liver volume, on gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) study, for the evaluation of liver function through the comparison with Child–Pugh (CP), model for end-stage liver disease (MELD), and biochemical tests. Methods: All dynamic Gd-EOB-DTPA MRI studies performed in patients with suspected liver lesions were retrospectively reviewed. The rate of liver-to-muscle ratio on T1 sequence 70 s (interstitial phase) and 20 min (hepatobiliary phase) after injection of Gd-EOB-DTPA was calculated for each MRI study and then normalized for liver volume (irINTnorm and irHEPnorm). Pearson correlation coefficient was computed to assess the correlation among these values and CP and MELD scores, and biochemical tests. Results: A total of 303 MRI studies, performed on 221 patients, were included. Mean age was 63.8 years ± 12.9 with a majority of male patients (186; 61.4%). A total of 186 out of 303 (61.4%) were cirrhotic patients. The irHEPnorm was significantly lower in cirrhotic than non-cirrhotic patients (0.0004 ± 0.0002 to 0.0005 ± 0.0003, p = 0.010). This value had a moderate, significant correlation with Child–Pugh and MELD scores (R = − 0.292, p < 0.0001 and R = − 0.192, p = 0.010, respectively). In particular, irHEPnorm progressively decreased from Child–Pugh A to C (0.0004–0.0002, p < 0.0001) and from MELD ≤ 10 to 19–24 (0.0004–0.0003, p = 0.018). Among biochemical parameters, total bilirubin, GOT, and albumin had the strongest correlation with irHEPnorm (R = − 0.258, − 0.291, and 0.262, p < 0.0001, respectively). No correlations were found between irINTnorm and CP and MELD scores. Conclusion: irHEPnorm value derived from Gd-EOB-DTPA-enhanced MRI is a reliable, non-invasive, useful tool to quantify liver function and to assess the degree of cirrhosis, offering a strict relationship with clinical scores and biochemical parameters. This could help surgeons in clinical decision-making, allowing them to choose the more suitable surgical approach for cirrhotic patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Impact of Liquid-Vapor to Liquid-Liquid-Vapor Phase Transitions on Asphaltene-Rich Nanoaggregate Behavior in Athabasca Vacuum Residue + Pentane Mixtures

The bulk phase behavior of heavy oil + alkane mixtures and the behavior of the asphaltenes that they contain are topics of importance for the design and optimization of processes for petroleum production, transport, and refining and for performing routine saturates, aromatics, resins, and asphaltenes (SARA) analyses. In prior studies, partial phase diagrams and phase behavior models for Athabasca vacuum residue (AVR) comprising 32 wt % pentane asphaltenes + n-alkanes were reported. For mixtures with pentane, observed phase behaviors included single-phase liquid as well as liquid–liquid, liquid–liquid–vapor, and liquid–liquid–liquid–vapor regions. Dispersed solids were detected under some conditions as well but not quantified. In this work, small-angle X-ray scattering (SAXS) is used to study nanostructured materials in liquid phases present in AVR + n-pentane mixtures from 50 to 170 °C at mixture bubble pressure. The investigation focuses on the impact of the transition from a single AVR-rich liquid to co-existing pentane-rich and AVR-rich liquids on the nanostructure and the nanostructures most resistant to aggregation as the pentane composition axis is approached. Background scattering subtraction was performed using global mixture composition. The robustness of this assumption with respect to values obtained for coefficients appearing in a two level Beaucage unified equation fit is demonstrated. The nanostructured material is shown to arise at two length scales from 1 to 100 wt % AVR. Smaller nanostructures possess mean radii less than 50 Å, while the larger nanostructures possess mean radii greater than 250 Å. The addition of pentane to the AVR causes an increasingly large fraction of the large and small nanostructures to grow in size. Only nanostructures resistant to aggregation remain in the pentane-rich phase as the 0 wt % AVR axis is approached. Step changes in aggregation identified from changes in average radius of gyration, scattering coefficients, and surface/volume ratios arise at the liquid–vapor to liquid–liquid–vapor transition (~40 wt % pentane) and within the liquid–liquid–vapor region (~90 wt % pentane). The temperature is shown to have a limited effect on the mean size and structure of the nanostructured material present, irrespective of global composition.

Long, Bingwen↗
DOE OSTI2022

Controlling the Phase Transition in CsPbI 3 Nanowires

Cesium lead iodide (CsPbI 3 ) is a promising semiconductor with a suitable band gap for optoelectronic devices. CsPbI 3 has a metastable perovskite phase that undergoes a phase transition into an unfavorable nonperovskite phase in an ambient environment. This phase transition changes the optoelectronic properties of CsPbI 3 and hinders its potential for device applications. Therefore, it is of central importance to understand the kinetics of such instability and develop strategies to control and stabilize the perovskite phase. Here, we use ultralong CsPbI 3 nanowires as a model platform to investigate the phase transition kinetics. Our results depict the role of environmental stressors (moisture and temperature) in controlling the phase transition dynamics of CsPbI 3 , which can serve as guiding principles for future phase transition studies and the design of related photovoltaics. Furthermore, we demonstrate the controllability of phase propagation on individual nanowires by varying the moisture level and temperature.

36 MATERIALS SCIENCE↗