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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Variations in proton transfer pathways and energetics on pristine and defect-rich quartz surfaces in water: Insights into the bimodal acidities of quartz

Hypothesis. Understanding the mechanisms of proton transfer on quartz surfaces in water is critical for a range of processes in geochemical, environmental, and materials sciences. The wide range of surface acidities (>9 pKa units) found on the ubiquitous mineral quartz is caused by the structural variations of surface silanol groups. Molecular scale simulations provide essential tools for elucidating the origin of site-specific surface acidities. Simulations. Here, we used density-functional tight-binding-based molecular dynamics combined with rare-event metadynamics simulations to probe the mechanisms of deprotonation reactions from ten representative surface silanol groups found on both pristine and defect-rich quartz (1 0 1) surfaces with Si vacancies. Findings. The results show that deprotonation is a highly dynamic process where both the surface hydroxyls and bridging oxygen atoms serve as the proton acceptors, in addition to water. Deprotonation of embedded silanols through intrasurface proton transfer exhibited lower pKa values with less H-bond participation and higher energy barriers, suggesting a new mechanism to explain the bimodal acidity observed on quartz surface. Defect sites, recently shown to comprise a significant portion of the quartz (1 0 1) surface, diversify the coordination and local H-bonding environments of the surface silanols, changing both the deprotonation pathways and energetics, leading to a wider range of pKa values (2.4 to 11.5) than that observed on pristine quartz surface (10.4 and 12.1).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Heat-induced drift reduction of time of flight in fused quartz acoustic waveguides via annealing process

High temperature structural acoustic sensors play an important role in many applications. Fused quartz waveguide is a popular choice due to its resistance to harsh environments and its convenience of modification. However, time of flight between pulse and echo, which is widely used in these sensors, tends to encounter drifts in fast temperature changing process even after temperature returns to initial value. In this article, different annealing process are performed for a special modified fused quartz waveguide with a sensor node. Annealing treatment is found able to reduce the drift when the waveguide undergoes a sudden temperature spike to 1000 °C at 500 kHz operating acoustic frequency, and the best annealing condition could make the drift one magnitude smaller. A following temperature test up to 1000 °C shows consistent measurement readings.

Hileman, Zachary (ORCID:0000000226529274)↗
DOE OSTI2020

Vertical effective stress and temperature as controls of quartz cementation in sandstones: Evidence from North Sea Fulmar and Gulf of Mexico Wilcox sandstones

Here we present quantitative petrographic data, high spatial resolution oxygen isotope analyses of quartz cement, basin modelling and a kinetic model for quartz precipitation for two Paleocene-Eocene Wilcox Group sandstones from Texas and two Jurassic Fulmar Formation sandstones from the Central North Sea. At each location, one sandstone has been buried to ca. 145 °C and one to ca. 185 °C. A key difference between the Wilcox and Fulmar burial histories is that the Wilcox sandstones are currently at higher vertical effective stresses and, from basin modelling studies, have been subjected to generally higher vertical effective stresses through their burial history. The amounts of quartz cement in the Wilcox sandstones are between 12 and 18%, and between 2 and 6% in the Fulmar sandstones. High-spatial-resolution oxygen isotope data obtained from the quartz cements suggest temperature ranges for quartz precipitation from 60 to 80 °C to values approaching maximum burial temperature. Factors such as grain coatings or the timing of petroleum emplacement cannot explain the differences in the amounts of quartz cement. Petrographic data show that most of the silica for quartz cement can be derived from intergranular pressure dissolution. Although the sample set is small, we interpret the results to suggest that the differences in quartz cementation in Fulmar and Wilcox sandstones can be explained better by differences in their vertical effective stress history than their temperature history; in this case, the supply of silica rather than the precipitation of quartz becomes an important control on the rate and extent of cementation.

58 GEOSCIENCES↗
DOE OSTI2022

Effect of Quartz Aperture Covers on the Fluid Dynamics and Thermal Efficiency of Falling Particle Receivers

Falling particle receivers are an emerging technology for use in concentrating solar power systems. In this paper, quartz half-shells are investigated for use as full or partial aperture covers to reduce receiver thermal losses. Quartz half-shell aperture covers offer the ability to minimally interfere with incoming solar radiation from the heliostat field while obstructing thermal radiation and advection from leaving the receiver cavity. The fluid dynamics and heat transfer of a receiver subdomain and surrounding air are modeled using ANSYS®FLUENT We compare the percentage of total incident solar power lost due to conduction through the receiver walls, advective losses through the aperture, and radiation exiting the aperture. Contrary to expected outcomes, results show that quartz aperture covers can increase radiative losses and result in modest to nonexistent reductions in advective losses. The increased radiative losses are driven by elevated quartz half-shell temperatures and have the potential to be mitigated by active cooling and/or material selection. Quartz half-shell total transmissivity was measured experimentally using a radiometer and the National Solar Thermal Test Facility heliostat field with values up to 0.97 ± 0.01. Quartz half-shell aperture covers did not yield expected efficiency gains in numerical results due to increased radiative losses, but efficiency improvement in some numerical results and the performance of quartz half-shells subject to concentrated solar radiation suggest that quartz half-shell aperture covers should be investigated further.

14 SOLAR ENERGY↗
DOE OSTI2025

A microstructural signature of the coesite-quartz transformation: New insights from high-pressure experiments and EBSD

Ultra-high pressure (UHP) metamorphism is difficult to identify in continental crust as few petrological barometers are suitable for dominantly felsic lithologies. In such cases, burial to extreme depths is commonly identified through the preservation of coesite, a high-pressure polymorph of SiO 2 that typically forms at depths exceeding ∼ 100 km (i.e., > 2 GPa pressure). Unfortunately, coesite readily transforms to quartz upon exhumation, meaning that UHP terranes may often be overlooked. While some studies have suggested that quartz may inherit an orientation signature indicative of former coesite, both the specific nature of this signature and the conditions favouring its development remain uncertain. Here, to address this problem, we combine electron backscatter diffraction analysis of natural and experimental samples to explore microstructural evolution across the coesite-quartz phase transformation. We demonstrate that neighbouring domains of quartz commonly feature an 84 ± 4° rotation of [c] axes around the pole of a common {m} plane. This orientation relationship is a product of epitaxy, whereby the {$11\bar{2}2$} Japan twin plane in quartz nucleates on the (010) plane in coesite. In supercell simulations, the nucleation of Japan twins can be explained by the energetically favourable alignment of quartz tetrahedra on parental coesite tetrahedra. Through experiments, we demonstrate that this signature emerges over a broad range of conditions, regardless of the availability of nucleation sites (e.g., grain boundaries) or the density of crystal lattice defects (e.g., dislocations). Overall, our work provides a quantitative and unambiguous tool for identifying UHP terranes from quartz in isolation.

Coesite↗
DOE OSTI2026

Mapping the Residual Stress Distribution in Polycrystalline Quartz Tiger's Eye Using Raman Spectroscopy

Stress distribution maps in polycrystalline materials are needed to reveal stress pathways caused by short‐and long‐range interactions of crystallites. Stress induced changes to wavenumbers in Raman spectroscopy is a well‐known phenomenon that occurs when a crystalline material undergoes elastic strain. Using spatially resolved Raman spectroscopy, we have developed a technique to experimentally measure grain‐scale residual stresses across a sample of polycrystal quartz Tiger's Eye. The results of this technique are validated using multiple criteria, including evaluation of the residual stress map itself and the accuracy of the measurements taken. The residual map of Tiger's Eye shows striking similarity to observed characteristics of other polycrystalline residual stress distributions, revealing heterogenous areas of high and low magnitude stresses. The stress magnitudes are consistent with residual stress magnitudes previously measured from polycrystalline quartz. Characterization of Tiger's Eye quartz also revealed the geometric nature of the iron oxide inclusions, not previously observed in Tiger's Eye quartz. With this technique, we present a residual stress map of Tiger's Eye quartz that shows with accuracy a heterogeneous stress state with inter‐ and intra‐granular detail.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Stressful crystal histories recorded around melt inclusions in volcanic quartz

Abstract Magma ascent and eruption are driven by a set of internally and externally generated stresses that act upon the magma. We present microstructural maps around melt inclusions in quartz crystals from six large rhyolitic eruptions using synchrotron Laue X-ray microdiffraction to quantify elastic residual strain and stress. We measure plastic strain using average diffraction peak width and lattice misorientation, highlighting dislocations and subgrain boundaries. Quartz crystals across studied magma systems preserve similar and relatively small magnitudes of elastic residual stress (mean 53–135 MPa, median 46–116 MPa) in comparison to the strength of quartz (~ 10 GPa). However, the distribution of strain in the lattice around inclusions varies between samples. We hypothesize that dislocation and twin systems may be established during compaction of crystal-rich magma, which affects the magnitude and distribution of preserved elastic strains. Given the lack of stress-free haloes around faceted inclusions, we conclude that most residual strain and stress was imparted after inclusion faceting. Fragmentation may be one of the final strain events that superimposes stresses of ~ 100 MPa across all studied crystals. Overall, volcanic quartz crystals preserve complex, overprinted deformation textures indicating that quartz crystals have prolonged deformation histories throughout storage, fragmentation, and eruption.

58 GEOSCIENCES↗
DOE OSTI2020

Simulations and Experiments Reveal Effect of Nanopores on Helium Diffusion in Quartz

The diffusion properties of noble gases in minerals are widely used to reconstruct the thermal histories of rocks. In this work, we combine density functional theory (DFT) calculations with laboratory experiments to investigate controls on helium diffusion in quartz. DFT calculations for perfect α-quartz predict substantially lower activation energies and frequency factors for helium diffusion than observed in laboratory experiments, especially in the [001] direction. These results imply that no helium could be retained in quartz at Earth surface temperatures, which conflicts with observations of partial cosmogenic 3 He retention over geologic time scales. Here, we implement a model of helium diffusion in α-quartz modulated by nanopore defects that disrupt energetically favorable diffusion pathways. In this model, we find that laboratory-determined diffusivities can be most closely reproduced when a helium atom encounters ~70 nanopore sites per million interstitial sites. The results of our model indicate that diffusion of helium in natural quartz, like other noble gases in other minerals, can be significantly modulated by extended defects.

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

Modeling Contact Angle vs. Temperature for the Quartz-Water-Decane System

Innovative approaches are needed to improve the efficiency of oil recovery technologies to meet the growing demands of fossil-fuel based energy consumption. Enhanced oil recovery (EOR) methods such as low-salinity waterflooding and chemically tuned waterflooding aim to optimize the reservoir’s wetting properties, detaching oil globules from rock surfaces and allowing easier oil flow through pore throats. This wetting behavior is commonly quantified by contact angle measurements of the rock-oil-brine interface, which have been thoroughly investigated and theorized for many systems at ambient temperatures and pressures. However, few studies exist for extending contact angle theories away from ambient conditions. In this paper, we model the contact angles of a quartz-water-decane system at elevated temperatures using the surface tension component (STC) approach. Temperature-dependent van der Waals [Lifshitz-van der Waals (LW)] interactions and hydrogen-bonding (acid-base) interactions were calculated and are incorporated into the model for the quartz-water-decane interface. Additionally, the Hough and White procedure was used to create temperature-dependent dielectric functions of quartz, water, and normal decane for calculations of Hamaker coefficients. Hamaker coefficients calculated this way are highly linear with temperature and agree well with Israelachvili’s approximation. The acid-base interactions likely contribute the most to system wettability changes. Resulting contact angles of the quartz-water-decane system shift from water-wet (16°) to slightly water-wet (57.4°) as temperature increases. The model was also successfully verified for the quartz-air-water system. Our results can be used in future studies to determine optimal injected water compositions for specific rock-oil-brine and other systems with consideration of reservoir temperature.

02 PETROLEUM↗
DOE OSTI2021

Density Functional Tight-Binding Simulations Reveal the Presence of Surface Defects on the Quartz (101)–Water Interface

Understanding the structure and reactivity of quartz–water interfaces is critical for numerous applications in the geological, environmental, and biological sciences. However, disagreements on the atomic-level structure of the interfaces between experiments and simulations are hampering our ability to predict the surface reactivity. Here, we used density functional tight-binding (DFTB)-based molecular dynamics to simulate a series of quartz (101) surfaces having different types and densities of surface defects in water and compared them with the structures determined by X-ray reflectivity measurements. The DFTB simulations are able to reproduce previous classical and quantum mechanical predictions of the pristine quartz (101)–water interface that disagree with experimental observations. To remedy this situation, a set of defective quartz surfaces having various surface silicon (Si) vacancies were built as indicated by recent experimental studies. We found that the rotation of surface [SiO 4 ] tetrahedra near Si vacancies can lead to outward displacements of Si atoms similar to those observed in the experiments. The presence of additional surface Si vacancies caused inward relaxations of terminal oxygens through the formation of hydrogen bonds. Finally, the overall results indicate that the quartz (101)–water interface may include a mixture of geminal (≡Si–(OH) 2 )- and vicinal (≡Si–OH)-type silanol groups together with the presence of surface Si vacancies.

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

Corrosive Influence of Carbon Dioxide on Crack Initiation in Quartz: Comparison With Liquid Water and Vacuum Environments

The stimulation of crack growth in quartz and siliceous materials by injecting carbon dioxide (CO 2 ) represents a key technology in long-term carbon storage and in the development of natural gas wells. While this technology is widely used, the molecular impact of CO 2 interactions on the solid matrix is only incompletely understood. In this work, we employ reactive molecular dynamics simulations to study how the CO 2 fluid environment affects the mechanical properties of pre-cracked single-crystal quartz. The thermodynamic conditions of interest are those relevant to subsurface reservoirs. We report how structural properties of quartz—bond length distribution and crack tip shape—evolve upon introduction of a fluid. These properties are directly related to macroscopic quantities of the global stress-strain curves, thus reaffirming the inherent coupling across multiple scales for fluid-solid interactions in the subsurface. Here, we find that CO 2 reduces the fracture toughness of quartz by 12.1% compared to that of quartz in vacuum, thereby promoting crack growth and enhancing fluid transport in the subsurface.

58 GEOSCIENCES↗
DOE OSTI2024

Fabrication and Testing of a Stainless Steel Quartz Coaxial Cable Structure for High Temperature Measurement

This paper presents a stainless-steel quartz coaxial cable structure for distributed sensing of high temperatures. The coaxial cable sensor uses stainless steel as the inner and outer conductors and quartz as the insulator in order to achieve mechanical strength and temperature resilience. Girdle-shaped reflectors are fabricated on the quartz tubing by CNC grinding and CO 2 laser resurfacing. The sensor operates by measuring the temperature dependent change in the effective electromagnetic length between the two adjacent reflectors on the quartz tubing. A retaining collar is fabricated at the tip of the quartz tubing by 3D printing and laser resurfacing to secure the connection between the sensor and the signal cable. The prototype sensor was tested for high temperature measurements up to 600°C, and the performance characteristics of the sensor such as sensitivity, resolution uncertainty, repeatability, and stability were estimated based on the test results.

Jiao, Xinyu↗
DOE OSTI2022

Gamma-radiation-induced negative nonlinear absorption in quartz glass

The effect of ionizing radiation on the nonlinear optical properties of materials needs to be considered for applications that employ high-power laser pulses in extreme radiation environments. The Heraeus Infrasil302 optical quartz glass was irradiated by gamma rays, and its nonlinear absorption was measured using the open-aperture Z-scan technique with nanosecond laser pulses. Irradiation results in a negative nonlinear absorption coefficient whose magnitude increases with irradiation dose. Nonlinear absorption coefficients of -0.78, -1.14, -1.29, and -1.88~ × ~10 -13 m/W are measured for gamma doses of 600 krad, 1.2 Mrad, 3.6 Mrad, and 10 Mrad, respectively. Thermal annealing restores the optical properties of quartz-glass to their unirradiated values. It is suggested that metallic impurities introduced by the manufacturing process have a role in inducing saturated absorption in irradiated quartz glass, which manifests as negative nonlinear absorption coefficient, and is demonstrated by comparing Infrasil302 quartz results to equivalent irradiated measurements for Spectrosil2000 quartz.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

E-beam-enhanced solid-state mechanical amorphization of α-quartz: Reduced deformation barrier via localized excess electrons as network modifiers

Under hydrostatic pressure, α-quartz (α-SiO 2 ) undergoes solid-state mechanical amorphization wherein the interpenetration of [SiO 4 ] 2- tetrahedra occurs and the material loses crystallinity. This phase transformation requires a high hydrostatic pressure of 14GPa because the repulsive forces resulting from the ionic nature of the Si–O bonds prevent the severe distortion of the atomic configuration. Herein, we experimentally and computationally demonstrate that e-beam irradiation changes the nature of the interatomic bonds in α-quartz and enhances the solid-state mechanical amorphization at nanoscale. Specifically, during in situ uniaxial compression, a larger permanent deformation occurs in α-quartz submicron pillars compressed during e-beam irradiation than in those without e-beam irradiation. Microstructural analysis reveals that the large permanent deformation under e-beam irradiation originates from the enhanced mechanical amorphization of α-quartz and the subsequent viscoplastic deformation of the amorphized region. Further, atomic-scale simulations suggest that the delocalized excess electrons introduced by e-beam irradiation move to highly distorted atomic configurations and alleviate the repulsive force, thus reducing the barrier to the solid-state mechanical amorphization. In conclusion, these findings deepen our understanding of electron–matter interactions and can be extended to new glass forming and processing technologies at nano- and microscale.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Structural response of α-quartz under plate-impact shock compression

Because of its far-reaching applications in geophysics and materials science, quartz has been one of the most extensively examined materials under dynamic compression. Despite 50 years of active research, questions remain concerning the structure and transformation of SiO 2 under shock compression. Continuum gas-gun studies have established that under shock loading quartz transforms through an assumed mixed-phase region to a dense high-pressure phase. While it has often been assumed that this high-pressure phase corresponds to the stishovite structure observed in static experiments, there have been no crystal structure data confirming this. In this study, we use gas-gun shock compression coupled with in situ synchrotron x-ray diffraction to interrogate the crystal structure of shock-compressed α-quartz up to 65 GPa. Our results reveal that α-quartz undergoes a phase transformation to a disordered metastable phase as opposed to crystalline stishovite or an amorphous structure, challenging long-standing assumptions about the dynamic response of this fundamental material.

58 GEOSCIENCES↗
DOE OSTI2021

Quartz Clock Oscillator Design and Analysis

Engineers at Sandia National Laboratories (SNL) have used quartz - based clock oscillators in various missions since the 1980s. As such, the design of these frequency control devices requires a high degree of reliability and producibility. The quartz clock oscillators designed at SNL have evolved over many years and are currently developed in house and fabricated using SNLs internal CMOS foundry. They are designed to operate in harsh environments, including temperature, radiation, shock and vibration. This report documents the methodology behind the design of quartz clock oscillators developed at SNL and includes an overview of quartz resonator technology and usage guidelines and a detailed overview of oscillator circuits.

42 ENGINEERING↗
DOE OSTI2022

Quartz-hosted inclusions and embayments reveal storage, fluxing, and ascent of the Mesa Falls Tuff, Yellowstone

Quartz-hosted glasses from the Mesa Falls Tuff provide a geochemical window into the pre-eruptive magmatic system from one of Yellowstone's largest-volume caldera-forming eruptions. H 2 O and CO 2 concentrations, along with major and trace elements, were measured in both fully enclosed glass inclusions and partially enclosed embayments in the same quartz crystals. Major elements are largely consistent between the inclusions and embayments, except for K 2 O and Na 2 O. Of note, K 2 O is enriched by ~1 wt.% in embayment interiors relative to inclusions. Most trace elements are also enriched in the embayment interiors compared to inclusions from the same crystals. Fractionation trends of trace elements are consistent with ~30-60% crystallization. Quartz-hosted glass inclusions preserve 3.1±0.9 wt.% H 2 O and 493±227 ppm CO 2 whereas embayment interiors have 0.9±0.1 wt.% H 2 O and 399±229 ppm CO 2 . The CO 2 is roughly similar, but the distinct ~2 wt.% discrepancy between inclusion and embayment interior H 2 O contents may have been produced by CO 2 fluxing sourced from underplated Yellowstone basalts. H 2 O gradients within embayments are flat in their interiors and modified by sharp positive gradients near embayment exteriors which were produced by post-eruptive rehydration. CO 2 gradients occur as gently sloping concentration gradients that extend inward 150 to 250 μm from the embayment exterior. Finally, finite-difference 1D and 2D diffusion modeling indicates the distribution of H 2 O and CO 2 in embayments was produced by slow, fluid-saturated decompression that preceded rapid ascent during the caldera-forming eruption.

2D diffusion modeling↗