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At least 109 records · Page 6

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DOE OSTI2019

High x-ray resolving power utilizing asymmetric diffraction from a quartz transmission crystal measured in the 6 keV to 22 keV energy range

We report a Cauchois-type spectrometer utilizing the (203) lattice planes at an oblique angle of 11.53° to the normal to the surface of a quartz transmission crystal recorded the Kα and Kβ spectral lines of six elements from Fe to Ag in the 6–22 keV energy range from a laboratory x-ray source. After deconvolving the natural lifetime widths and the image plate detector broadening from the observed spectral linewidths, the intrinsic crystal resolving power was determined to be 4000 at the lower energies and decreasing to 1000 at the higher energies. Previously, a Si wafer crystal exhibited twice this resolving power when the (331) planes had been used in asymmetric geometry. The investigation of diffraction with this quartz crystal, with a very similar lattice spacing and therefore spectral coverage, was motivated by the larger integrated reflectivity of quartz due to its well-known quasimosaicity upon elastic bending. The measured spectral linewidths were in good agreement with the widths calculated by accounting for various broadening mechanisms, including source size, crystal thickness, crystal height, crystal rocking curve width, geometrical aberrations, and possible spectrometer configuration errors. This is the first, to the best of our knowledge, demonstration of high resolving power achieved by asymmetric diffraction over a wide energy range (6–22 keV) and with detailed comparisons with theoretical broadenings. Finally, based on these results, Cauchois spectrometers employing asymmetric planes of perfect quartz and silicon crystals can be reliably designed and optimized for high-resolution spectroscopy in the >6 keV energy range.

36 MATERIALS SCIENCE↗

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↗

NASA NTRS1975

Asymmetric adsorption by quartz - A model for the prebiotic origin of optical activity

One mechanism previously proposed for the abiotic accumulation of molecules of one chirality in nature is asymmetric adsorption on the chiral surfaces of optically active quartz crystals. Earlier literature in this field is reviewed, with the conclusion that previous investigations of this phenomenon, using optical rotation criteria, have afforded ambiguous results. We now have studied the adsorption of radioactive D- and L-alanine on powdered d- and l-quartz, using change in radioactivity level as a criterion for both gross and differential adsorption, d-Quartz preferentially adsorbed D-alanine from anhydrous dimethyl-formamide solution, and l-quartz L-alanine. The differential adsorption varied between 1.0 and 1.8%. The implications of these observations are discussed from the viewpoint of early chemical evolution and the origin of optically active organic compounds in nature.

Bonner, W. M.↗

NASA NTRS1989

Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?

Quartz pebbles from the Roter Kamm impact crater (the Namib Desert, SWA/Namibia) were examined for evidence of impact-induced hydrothermal activity, using results from microprobe analyses, neutron activation analyses, transmission IR spectroscopy, and X-ray diffractometry. It was found that the pebbles consisted of pure quartz, which contains three different types of fluid inclusions. These were identified as primary inclusions (5-10 microns) that record the formation conditions of the quartz, very small (less than 1 micron) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. It is concluded that the quartz and the primary inclusions may provide evidence for a postimpact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

Koeberl, Christian↗

NASA NTRS1991

Study of factors determining the radiation sensitivity of quartz crystal oscillators (AO189)

Quartz resonators fabricated from two different grades of quartz material and selected for their susceptibility to radiation damage as determined by transmission electron microscopy (TEM), were tested prior to the LDEF flight. These resonators were then flown on the LDEF mission where they were exposed to the radiation environment of low Earth orbit. Post-flight tests were then conducted to determine any differences in resonator performance caused by the space exposure. Results of the TEM analysis of the quartz material and preflight and postflight measurements of the flight resonators and of the space and ground based control resonators are presented. Further planned work on the TEM analysis of the quartz materials will also be outlined.

Ahearn, J. S.↗

NASA NTRS1992

Study of factors determining the radiation sensitivity of quartz crystal oscillators (A0189)

Previous postflight tests of quartz resonators fabricated from swept premium Q quartz were affected by the space radiation environment experienced on the Long Duration Exposure Facility (LDEF) flight. Resonators fabricated from natural quartz materials were not. The resonant frequency of the swept premium Q material exposed to the space radiation exhibited a change in frequency that was significantly larger than that of the controls or the natural crystal material and the frequency change was attributed to a recovery of damage to the quartz material sustained during the LDEF flight. Further tests of the resonators, currently in progress, are being conducted to verify this conclusion, the results of which will be presented at the LDEF Symposium.

Ahearn, J. S.↗

NASA NTRS1992

Chemical isolation of quartz for measurement of in-situ-produced cosmogenic nuclides

An isolation method relying totally on chemical steps was developed to separate large quantities (10-200 g) of clean mono-minerallic quartz samples from a variety of terrestrial rocks and soils for the purpose of measuring Be-10 (t1/2 = 1.5 Myr) and Al-26 (t1/2 = 0.705 Myr) produced by cosmic rays in situ in the quartz phase. The procedure consists of grinding the sample, heating it in HCl, and treating it with a series of leaches using a dilute HF/HNO3 mixture in a heated ultrasonic tank. The purified quartz was also used for the measurements of in situ cosmic-ray-produced Ne-21 and C-14 (t1/2 = 5730 yr). The method is applicable to any problem requiring purified quartz on a large scale.

Kohl, C. P.↗

NASA NTRS1993

Quartz dissolution. I - Negative crystal experiments and a rate law. II - Theory of rough and smooth surfaces

The range of the measured quartz dissolution rates, as a function of temperature and pOH, extent of saturation, and ionic strength, is extended to cover a wider range of solution chemistries, using the negative crystal methodology of Gratz et al. (1990) to measure the dissolution rate. A simple rate law describing the quartz dissolution kinetics above the point of zero charge of quartz is derived for ionic strengths above 0.003 m. Measurements were performed on some defective crystals, and the mathematics of step motion was developed for quartz dissolution and was compared with rough-face behavior using two different models.

Gratz, Andrew J.↗

NASA NTRS1995

Millimeter And Submillimeter-Wave Integrated Circuits On Quartz

Proposed Quartz substrate Upside-down Integrated Device (QUID) relies on UV-curable adhesive to bond semiconductor with quartz. Integrated circuits including planar GaAs Schottky diodes and passive circuit elements (such as bandpass filters) fabricated on quartz substrates. Circuits designed to operate as mixers in waveguide circuit at millimeter and submillimeter wavelengths. Integrated circuits mechanically more robust, larger, and easier to handle than planar Schottky diode chips. Quartz substrate more suitable for waveguide circuits than GaAs substrate.

Mehdi, Imran↗

NASA NTRS2003

Diaplectic Glass Content in Experimentally Shock-loaded Quartz Determined by X-Ray Powder Diffraction

Quartz is the most common mineral of terrestrial crustal rocks and thus a widespread indicator for impact cratering and associated shock metamorphism. Planar deformation features (PDFs) are among the most prominent and diagnostic shock features in quartz and they represent thin lamellae of glass that formed via solid-state transformations. This socalled 'diaplectic' glass becomes pervasive at higher pressures and results in optically isotropic and X-ray-amorphous phases that resemble texturally the original quartz grains (without evidence of melt flow). In the past, it has been shown that the amount of this amorphous material in experimentally shock-loaded quartz correlates with peak shock pressure. Both reports derive the glass content from density measurements of individual crystals employing the equation X(%) = (rho(sub x) - rho(sub 0))/(rho(sub x) - rho(sub gl)), where x and 0 stands for X-ray and average (optical) density, respectively. The density of glass, rho(sub gl), was adopted as 2.2 g/cu cm. Though the same procedures had been applied, the resulting glass content differs significantly among the above studies. In the present study, we are using a new approach based solely on the integral intensity of a single, carefully selected reflection in the XRD pattern, and we will compare our data to those reported in the literature.

Skala, R.↗

DOE OSTI2015

Water contact angles on quartz surfaces under supercritical CO 2 sequestration conditions: Experimental and molecular dynamics simulation studies

The ambiguity of contact angle experimental measurements due to surface chemistry changes resulted from sample contamination and/or the degrees of reaction with supercritical CO 2 has resulted in great difficulties to precisely understand the wetting behavior of CO 2 under the geological carbon sequestration (GCS) conditions. Water contact angles on quartz surface under GCS conditions were investigated through the combined experimental and molecular dynamics simulation (MDS) methods. The experimental results show that water contact angles increases as ionic strength increases. The effects of pressure and temperature are very weak. The dependence of ionic strength, pressure and temperature is same for monovalent and divalent ions solutions. In the MDS, a hydroxylated quartz surface was used as the base point. A good agreement between the MDS and experimental results were obtained. Using the MDS method, a clean mineral surface with a desired surface chemistry can be constructed, which is difficult in experiments. So by comparing MDS and experimental results, the mechanisms of the reservoir wettability can be better understood. Further investigation can be made on quartz surface with different functional groups to better understand wettability alteration caused by contamination and/or CO 2 reaction.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

Humidity scanning quartz crystal microbalance with dissipation monitoring setup for determination of sorption-desorption isotherms and rheological changes

A new method to determine water sorption-desorption isotherms with high resolution in the complete range of water activities (relative humidities) is presented. The method is based on quartz crystal microbalance with dissipation monitoring (QCM-D). The QCM-D is equipped with a humidity module in which the sample film is kept in air with controlled humidity. The experimental setup allows for continuous scanning of the relative humidity from either dry to humid conditions or vice versa. The amount of water sorbed or desorbed from the sample is determined from the resonance frequencies of the coated quartz sensor, via analysis of the overtone dependence. In addition, the method allows for characterization of hydration induced changes of the rheological properties from the dissipation data, which is closely connected to the viscoelasticity of the film. The accuracy of the humidity scanning setup is confirmed in control experiments. Sorption-desorption isotherms of pig gastric mucin and lysozyme, obtained by the new method, show good agreement with previous results. Finally, we show that the deposition technique used to coat the quartz sensor influences the QCM-D data and how this issue can be used to obtain further information on the effect of hydration. In particular, we demonstrate that spin-coating represents an attractive alternative to obtain sorption-desorption isotherms, while drop-coating provides additional information on changes of the rheological properties during hydration.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

Mathematical modeling of quartz particle melting process in plasma-chemical reactor

Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ r{sub p} ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ r{sub p} ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

42 ENGINEERING↗

DOE OSTI2017

Irradiation- vs. vitrification-induced disordering: The case of α-quartz and glassy silica

Irradiation and vitrification can both result in the disordering of minerals. However, it remains unclear whether these effects are comparable or if the glassy state represents an upper limit for irradiation-induced disordering. By reactive molecular dynamics simulations, we compare the structure of irradiated quartz to that of glassy silica. We show that although they share some degree of similarity, the structure of irradiated quartz and glassy silica differs from each other, both at the short- (<3 Å) and the medium-range (>3 Å and <10 Å). In particular, the atomic network of irradiated quartz is found to comprise coordination defects, edge-sharing units, and large rings, which are absent from glassy silica. These results highlight the different nature of irradiation- and vitrification-induced disordering.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2015

Acousto-optic diffraction of multicolour Ar-laser radiation in crystalline quartz

We have studied acousto-optic Bragg diffraction of multicolour radiation, generated by an Ar laser in the blue-green region of the spectrum, on an acoustic wave propagating in crystalline quartz. It is shown that crystalline quartz significantly exceeds commonly used paratellurite in terms of phase matching of optical beams with a single acoustic wave. We have performed experiments on pulse modulation of Ar-laser radiation. It is shown that distortions introduced into optical pulses are substantially less when use is made of a quartz crystal rather than paratellurite. (acoustooptics)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Active feedback cooling of massive electromechanical quartz resonators

We present a general active feedback cooling scheme for massive electromechanical quartz resonators. We cool down two kinds of macrosized quartz tuning forks and find several characteristic constants for this massive quartz-resonator feedback cooling, in good agreement with theoretical calculations. When combined with conventional cryogenic techniques and low-noise devices, one may reach the quantum sensitivity for macroscopic sensors. This may be useful for high sensitivity measurements and for quantum information studies.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2018

Behavior of Hydroxyl Groups in Quartz Glass during Heat Treatment in the Range 750–950°C

The concentration of hydroxyl groups in different types of quartz glass tubes, the OH concentration profile across the tube wall, and the kinetics of OH removal during heat treatment in the temperature range 750–950°C have been studied by Fourier transform IR spectroscopy. For TK-I tubes, produced by vacuum electromelting of quartz, followed by annealing in a hydrogen atmosphere, we have calculated the diffusion coefficient of OH groups in this temperature range and the activation energy for diffusion: 215 ± 10 kJ/mol. We have found heat treatment conditions that ensure a considerable decrease in the concentration of OH groups in quartz tubes that are used in the fabrication of reactors for the preparation of extrapure chalcogenide glasses.

36 MATERIALS SCIENCE↗

DOE OSTI2011

The effect of chrome adhesion layer on quartz resonator aging.

This SAND report documents a late start LDRD designed to determine the possible aging effects of a quartz resonator gold adhesion layer. Sandia uses quartz resonators for applications. These applications require a very stable frequency source with excellent aging (low drift) characteristics. These parts are manufactured by one of our qualified vendors outside Sandia Laboratories, Statek Corp. Over the years we, Sandia and the vendor, have seen aging variations that have not been completely explained by the typical mechanisms known in the industry. One theory was that the resonator metallization may be contributing to the resonator aging. This LDRD would allow us to test and analyze a group of resonators with known differentiating metallization and via accelerated aging determine if a chrome adhesion layer used to accept the final gold plating may contribute to poor aging. We worked with our main vendor to design and manufacture a set of quartz resonators with a wide range of metallization thickness ratios between the chrome and gold that will allow us determine the cause of this aging and which plating thickness ratios provide the best aging performance while not degrading other key characteristics.

42 ENGINEERING↗