Quartz Crystal Deposition Research Articles

Age and generation conditions of quartz crystal deposits in the Subpolar Urals

Research subject. The Dodo and Puiva quartz crystal deposits in the Neroiskiy mineral province (Subpolar Urals) were studied. Although these deposits have received sufficient research attention, a number of issues remain to be elucidated, including the age of crystal-bearing mineralization and the age of host rocks. Aim. In this work, we aim to determine the age of the metasomatites that bear quartz crystal mineralization and to develop a model of the formation of the Dodo and Puiva deposits. Materials and Methods. 40Ar/39Ar dating was carried out according to the method described by A.V. Travin et al. The argon isotope composition was measured on a Micromass 5400 mass spectrometer (IGM SB RAS). Results. Microprobe studies of the mineralogy of the Dodo and Puiva quartz crystal deposits were carried out. The temperatures of meta-somtaite formation were determined to range within 339–364°C. Six main structural and morphological types of quartz veins were identified and described. The 40Ar/39Ar ages of mica of quartz crystal deposits and host metamorphic schists were determined. Reliable plateaus were obtained, the values of which ranged within 251–257 Ma and agreed with each other within the deviation (average for 4 dates is 255 ± 2 Ma). Conclusion. A new model for the formation of quartz crystal deposits in the Subpolar Urals is proposed. The obtained 40Ar/39Ar ages correspond to the period of the post-orogenic extension of the Urals. At that time, a system of meridional grabens and rifts was formed in the Urals and in the West Siberian Plate. At the same time, and as a result of the same stretching impulse, large blocks of the middle crust (granite, schist, etc.) were brought to the Earth’s surface in the Urals. During the rise of deep blocks, at a depth of 10 km, a sharp, approximately 3-fold drop in fluid pressures (from lithostatic to hydrostatic) and a strong decrease in temperatures due to adiabatic expansion and the throttling effect occurred. The obtained 40Ar/39Ar ages (255 Ma) reflect not only the age of the quartz crystal deposits of the Subpolar Urals, but also place the moment of rise of the entire Central Ural uplift above a depth of 10 km, i.e., to the level of the upper cortex.

Effect of independently controllable electrolyte ion content on the performance of all-solid-state electrochromic devices

All-solid-state electrochromic devices (ECDs) with new structure glass/ITO/NiO/Ta2O5/Li/WO3/ITO, which can independently control the content of electrolyte ion by using lithium (Li) metal as the electrolyte, are fabricated by e-beam and resistive evaporation method. In this ECD, tungsten oxide (WO3) and nickel oxide (NiO) are used as the electrochromic and complementary layer, respectively, and tantalum oxide between WO3 and NiO acts as the ion conductor layer. ECDs with different thickness of Li, measured by quartz crystal deposition monitor, are prepared to investigate the effect of Li content on the electrochromic performance. The electrochemical and optical performance are characterized and the results demonstrate that the thickness of Li electrolyte has a great influence on the transmittance modulation, response time and cycle stability of the device. The ECD with 40 nm Li shows the best electrochromic performance includes the high optical modulation, superior cycle stability (optical modulation reaches 52.6% after 500 cycles) and large coloration efficiency (97.9 cm2·C−1) at wavelength of 550 nm. The ECDs displays remarkable potential for application in the field of smart windows.

Tectonophysical criteria for forecasting the locations of quartz crystal deposits (case of Subpolar Ural)

Spatial reconstruction of tectonic stresses within the Subpolar Ural quartz crystal-containing province was conducted by the kinematic method [Gushchenko, 1973, 1979] based on the main indicators of tectonic stresses on slickensides. Local stress states (LSS) and general stress fields for large blocks were reconstructed by the method described in [Sim, Marinin, 2015]. In the blocks with numerous occurrences of quartz crystal (Pelingichey and Omega-Shor blocks), the general stress fields is characterized by a stress state close to uniaxial tension, i.e. the Lode-Nadai coefficient µ=–1. In these blocks, thick quartz veins are perpendicular to the tension axis of the general stress field. In the block without quartz crystal (West Saled), the general stress field is characterized by a triaxial stress state or pure shear state (–1˂µσ˂+1). The LSS of the quartz crystal deposits show the following: the stress state of µ=–1 is typical of quartz veins without quartz crystal nests, and a special kind of stress state is reconstructed near the nests with piezoelectric material. It is named a variation of the type of stress state (VTSS), which means that within one tectonic stage, the type of stress state changes approximately as follows: µσ=+1 (40 %), µσ=–1 (40 %), and –1˂µσ˂+1. It means that in the piezoelectric mineral deposits, pulsating tectonic stresses provided for a fluid flow of hydrothermal solutions at the intersection of ore-bearing and ore-controling faults when tension (µ=–1) was replaced with compression (µ=+1), while the orientations of compression and tension axes remained unchanged. Apparently, such a regime was caused by alternating activation of the above-mentioned faults. The tectonic stress reconstructions were performed for 33 mineral deposits and occur­rences of quartz crystal. VTSS was determined in 32 deposits; one mineral occurrence is characterized by uniaxial tension. Therefore, we propose using VTSS (variation of the type of stress state) as a criterion for predicting the locations of quartz crystal deposits.

Evaluation of explosive sublimation as the mechanism of nanosecond laser ablation of tungsten under vacuum conditions

A non-equilibrium mechanism for nanosecond laser ablation is suggested herein, and its predictions are compared to the results of W experiments performed under vacuum conditions. A mechanism of particle formation is explained via this model, with partial sublimation of the superheated irradiated zone of the target considered to be the mechanism of laser ablation. In this study, a mixture of vapor and particles was explosively generated and subsequently prevented the rest of a laser pulse from reaching its intended target. This mechanism was found to play an essential role in the ablation of W under vacuum conditions, and it provides a theoretical justification for particle formation. Moreover, special considerations were taken into account for the expansion of plasma into a vacuum. The model was evaluated by measuring the mass of ablated particles using a quartz crystal deposition monitor and time-resolved optical emission spectroscopy. The results of this model were found to be in good agreement with experimental values.

電離層プラズマ環境模擬のためのマイクロ波放電式酸素イオン源

In recent years, concern has been raised about the interference phenomena (chemical reaction, sputtering etc.) between ionospheric plasma and high-voltage space systems such as the International Space Station and so on. In order to solve the physical mechanisms of these phenomena and establish the prevention technology, it is important to accumulate experimental data based on ground simulation tests. Therefore we have developed a cathode-less microwave discharge oxygen ion source for an ionospheric plasma simulator. The oxygen ion source for ionospheric plasma simulation demands plasma density more than 1012m- 3 and high durability (our target is more than 70hours). This ion source is capable of generating oxygen plasma of the order of 1014m- 3 for more than 100hours with 25W microwave power and 3sccm oxygen gas. In order to investigate the operational performance of the oxygen ion source, we conduct various measurement tests such as plasma diagnosis using a single probe, ionic mass spectroscopy by a Quadrupole Mass Spectrometer (QMS), atomic oxygen flux measurement using a silver coated QCM (Quartz Crystal deposition Monitor) and 70hours operating test etc. This paper reports the experimental results of each measurement tests and assesses performance as an ion source for ionospheric plasma simulator.

Controlling the plasma chemistry of silicon nitride and oxide deposition from silane

We have studied the chemistry of glow discharge plasma-enhanced chemical vapor deposition (PECVD) by using vibrating quartz crystal deposition rate monitoring at 200–300 °C and line-of-sight mass spectrometry of orifice-sampled reactive neutral species. In the deposition of dielectric films from silane plus a large excess of oxidant (NH3, N2, or N2O), the key process factor is the ratio of plasma power to silane supply rate. When enough of the oxidant is activated by the plasma, it completely converts the silane to films which have no excess Si and no Si–H bonding. The critical ratio can be detected by the disappearance of Si2H6 byproduct or by the presence of excess activated oxidant. Nitride deposited from N2 is electrically leaky due to porous microstructure even when deposited using excess activated oxidant. Conversely, nitride deposited from NH3 is nonporous, and when deposited using excess activated oxidant it has a surprisingly low electron trapping rate which is at least as low as that achievable in PECVD oxide. Deposition using N2 involves no formation of gas-phase precursor molecules; but using NH3, •Si(NH2)3, and Si(NH2)4 were the dominant precursors. SiO2 deposition from N2O involved a minor contribution from Si(OH)4. High reactant partial pressure or excess rf power can lead to particle formation and deposition rate loss, especially in SiO2 deposition, due to gas-phase reaction among precursors. Partial pressure reduction either by He dilution or by total pressure reduction suppressed these problems with equal effectiveness in SiO2 deposition. No other effects of He could be detected either in the plasma chemistry or in the bulk film trapping rate.

Characterization of a radio frequency plasma source for molecular beam epitaxial growth of high-T c superconductor films

The growth of superconducting oxides in vacuum conditions compatible with molecular beam epitaxy (MBE) requires a form of activated oxygen. The activated oxygen species can be either atomic oxygen (O) or ozone (O3). Here we characterize a rf plasma source by measuring the oxidation rate of a silver film on a quartz crystal deposition monitor as a function of the oxygen flow. The initial oxidation rate provides a lower limit for the actual atomic oxygen flux. If the frequency change of the quartz signal is entirely due to the oxidation of silver by atomic oxygen and we assume a detection efficiency of one, then the total cracking efficiency of the source is estimated to be around 30%. The source was used in a MBE machine to deposit thin (200 Å) high-Tc films of DyBa2Cu3O7 on SrTiO3 with a Tonsetc of 88 K and a Tzeroc of 86 K.

Low carrier concentration (PbSn)Te by molecular beam epitaxy

pb0.77.77SN0.23Te was grown by evaporation of the pure elements or of the binary compounds from Knudsen cell sources at l0-10 torr. The growth chamber was provided with ion bombardment, LEED, Auger spectroscopy and quartz crystal deposition moni-toring. A Sn-wetted heating block was used for close control of substrate temperature. On chemomechanically-polished BaF2 (100) substrates, monocrystalline films smooth to tens of Angstroms were obtained at 1 micrometer/hour growth rate over a substrate temperature range from 300 to 420°C; above A20°C, re-evaporation occurred. In growth from the elements, excess Pb remains as droplets on the film surface, but most excess Te re-evaporates. The remaining Te produces Pb vacancies which generate p-carriers; conversely, excess Pb produces n-carriers. A quartz crystal deposition rate monitor operat-ing at the growth temperature was used to tune impinging (Te/ Pb+Sn) ratio by observing the discontinuity in rate vs. (Te/ Pb+Sn) which occurred at the stoichiometric ratio. This technique yielded films with as-grown carrier concentrations in the high l017 p/cm3 range at 77K. Closer stoichiometry control was obtained by growing from PbTe and SnTe sources with the use of a separate Pb source for reduction of inher-ent Te excess. For Pb0.77Sn0.23Te, The metal-rich single-phase boundary was found to cross the stoichiometric composition at 395 + 5°, so that only p-type material was obtainable above this temperature. By using 0.014 atomic fraction excess Pb, it was possible to constrain the film composition to this boundary and thus obtain close control over carrier concen-tration by appropriate adjustment of substrate temperature. Carrier concentrations of 2×l017/cc at 77K were obtained in this manner for both n- and p-type material. Excess Pb coalesced into droplets spaced sparsely enough on the sur-face so as not to interfere with device fabrication. Hall mobilities were about 1×104 cm2 /v⋅sec at 77K. Attempts to reduce carrier concentration below 2×1017 cm-3 resulted in anomalously low Hall voltages, suggesting existence of p and n domains in the films. The origins of this inhomogeneity are not clear at present.

Observations on a quartz crystal deposition monitor

A quartz crystal deposition monitor has been constructed which employs AT cut quartz plates resonating at 6 MHz. Results are given which show that a series of deposited mass against frequency change relationships can be produced depending upon the area of quartz crystal exposed to the vapour source. The calibrations reported were obtained using copper as the evaporant and the relationships between frequency change and deposited mass were found to be reproducible up to a total frequency change of approximately 160 kHz. Also reported is an investigation into the use of resonator impedance measurements for determining when the useful life of a monitor plate is to end.

Quartz crystal deposits in the state of Goiaz, Brazil

The three major quartz crystal producing regions in the state of Goiaz are on the central Brazilian plateau. Quartz crystal of commercial quality occurs as a minor constituent of quartz veins cutting Algonkian quartzites and Archean schists. Important production has been won from secondary deposits formed by weathering and erosion of the vein outcrops. Large inferred reserves of quartz crystal exist in north central and east central Goiaz.

The quartz crystal deposits of western Arkansas

Extensive geological investigations of domestic deposits of quartz crystals were undertaken by the Geological Survey of the United States Department of the Interior in the fall of 1942 in response to the urgent demand for crystals for war purposes. The work was continued throughout 1943 and took survey geologists into some 20 states in which over 1,400 deposits or reports of deposits were examined. Of the numerous highly varied occurrences of quartz examined, only the deposits in western Arkansas, in the Piedmont and Blue Ridge provinces of Virginia, North Carolina and Georgia and the placer quartz of Mokelumne Hill, California, were of sufficient promise to warrant detailed work. Production in 1943 from these areas totaled slightly less than 4 tons of oscillator quartz, over 85 per cent of which came from Arkansas.The Arkansas deposits occur throughout the thick, deformed Paleozoic shales, sandstones, and cherts exposed along the central belt of the Ouachita Mountains. Steeply dipping fractures closely related to the major folds control the deposition of most quartz.Clear quartz is confined largely to the terminal parts of primary crystals, which have developed without disturbance or interference, are commonly elongate parallel to their C axes and are bounded by relatively simple forms. Deposition of silica during and subsequent to the fracturing of crystals resulted in the formation of complex crystals which are characterized by extensive optical twinning and lineage structures, and commonly are bounded by aggregates of the simpler crystal forms. The principal defects in all types of crystals are twinning, smokiness, cavities, solid inclusions and fractures.The Arkansas quartz deposits include veins, sheeted zones and stock-works. They are largely cavity fillings, apparently deposited by rising, attenuated, hydrothermal solutions, at relatively low temperatures and pressures. Minerals associated with the quartz, which constitutes 90 per cent or more of the cavity fillings, include dickite and carbonaceous material, calcite, adularia, and chlorite. The constituents of the cavity fillings could have been derived principally from magmatic sources or more probably from underlying rocks, with small additions from the rocks enclosing the cavities. The complex vein fabrics apparently resulting from intermittent regional deformation during the deposition of the quartz, and certain structural relations of the deposits, indicate that they were formed in the final stages of the Ouachita orogeny, probably in mid-Pennsylvanian time.

The Discovery of Quartz Crystal Deposits and New Production Methods

The Discovery of Quartz Crystal Deposits and New Production Methods