Total Impurity Content Research Articles

Effects of Er2O3 content on heat capacity, thermodynamic functions and vitrification characteristics of Er3 +-doped tellurite glass

A series of samples of high-purity glasses TeO2-WO3-La2O3-Er2O3-Bi2O3 with different mole content of Er2O3 was synthesized. The total content of the 3d-transition metals impurities did not exceed 0.1–2ppm wt., the hydroxyl groups absorption near ~3μm was as low as 0.001–0.01cm−1. The glasses have been studied by differential scanning calorimetry. Glass transition temperatures were determined; for the highest Er2O3 concentrations the thermal effects of crystallization were observed at the heating rate of 5K/min. The temperature dependences of heat capacity C°p=f(T) in the range of 320–1050K were found. Using the experimental data the standard thermodynamic functions were calculated: enthalpy H°(T)−H°(0), entropy S°(T)−S°(0) and Gibbs energy G°(T)−G°(0) in vitreous and “supercooled liquid” states. Model and parametric similarity of properties within the framework of statistical approach with determined correlation dependencies of parameters on composition makes it possible to predict the thermodynamic functions for other compositions of glasses within the system.

Impurity composition of high-purity simple solids (elements) of group 13–16 Mendeleev periodic system

This paper discusses correlations in the impurity composition of the purest solid group 13–16 elemental substances so far, exemplified by a set of samples in the Exhibition–Collection of Extrapure Substances, a permanent exhibition. The abundance of particular elemental impurities in the samples of the high-purity substances has been determined. Dividing the entire set of impurities into classes, we have accurately determined integral characteristics (average and total concentrations) of impurities in the samples and evaluated the contribution of each impurity class to the total impurity concentration.

Impurity composition of the samples in the exhibition–collection of extrapure substances: I. samples of elemental substances received in 2007–2015

Data are presented on the purity of the samples of elemental substances, including isotopically enriched samples, received by the Exhibition–Collection of Extrapure Substances in 2007–2015. During this time period, the permanent exhibition received 26 samples of elemental substances from 11 institutes and research and production centers of Russia. The first samples of high-purity isotopically enriched silicon, germanium, sulfur, and selenium were provided. The total impurity concentration in the best samples is 3 × 10–5 to n × 10–4 at %. More than half of the new samples compare well to the current world level.

Refining of Rough Indium by Method of Reactionary Electrolysis

Electro-refining of rough indium by method of reactionary electrolysis from the chloride solutions containing InCl3 was carried out. The research of ionization of rough and modified indium anodes showed a decrease in an overvoltage of dissolution of indium when using the anodes containing bismuth. The values of the activation energy of the ionization stage of rough to 7.3 kJ / mole and the indium anodes modified by bismuth with 5- and 10-fold excess of depressor in relation to the total content of impurities, amounted to 5.6 and 3.7 kJ / mole, respectively. Results of the analysis of the refined indium by ICP-OES and ICP-MS methods showed that use of bismuth as a depressor additive allowed reducing impurity (Zn, Pb, Cd, Cu, Fe, Ni, As, Tl) level to 1.1 ppm.

Determination of D-lactide content in lactide stereoisomeric mixture using gas chromatography-polarimetry

An analytical method has been proposed to quantify the D-lactide content in a lactide stereoisomeric mixture using combined gas chromatography and polarimetry (GC- polarimetry). As for a lactide stereoisomeric mixture, meso-lactide can be determined quantitatively using GC, but D- and L-lactides cannot be separated by the given GC system. The composition of a lactide stereoisomeric mixture is directly relative to its specific optical rotation. The specific optical rotations of neat L-lactide were obtained in different solutions, which were −266.3° and −298.8° in dichloromethane (DCM) and toluene solutions at 20°C, respectively. Therefore, for a lactide sample, the D-lactide content could be calculated based on the meso-lactide content obtained from GC and the specific optical rotations of the sample and neat L-lactide obtained from polarimetry. The effects of impurities and temperature on the test results were investigated, respectively. When the total content of impurities was not more than 1.0%, the absolute error for determining D-lactide content was less than 0.10% in DCM and toluene solutions. When the D-lactide content was calculated according to the specific optical rotation of neat L-lactide at 20°C, the absolute error caused by the variation in temperature of 20±15°C was not more than 0.2 and 0.7% in DCM and toluene solutions, respectively, and thus usually could be ignored in a DCM solution. When toluene was used as a solvent for the determination of D-lactide content, a temperature correction for specific optical rotations could be introduced and would ensure the accuracy of results. This method is applicable to the determination of D-lactide content in lactide stereoisomeric mixtures. The standard deviation (STDEV) of the measurements is less than 0.5%, indicating that the precision is suitable for this method.

Growth of high optical quality zinc chalcogenides single crystals doped by Fe and Cr by the solid phase recrystallization technique at barothermal treatment

The method of growing of ZnS and ZnSe single crystals doped with chromium and iron using a combination of the solid phase recrystallization and diffusion doping during the high-temperature gas-static pressing has been implemented. The isostatic pressing up to 110MPa has made it possible to increase the process temperature up to 1300°C, increase the rate of grain growth and diffusion of Fe2+ and Cr2+ ions in zinc chalcogenides crystalline samples, reduce processing time to 25–150h. ZnS:Cr (Fe) and ZnSe:Cr (Fe) single crystals from several to tens mm in size with dopant concentrations of (1–5)×1019cm−3 for Cr2+ and (5–20)×1018cm−3 for Fe2+ and at the total impurity's content no more than 5×10−4wt% have been obtained. The lasers made from the crystals demonstrated 55% differential lasing efficiency for the absorbed power.

Amorphous silica containers for germanium ultrapurification by zone refining

We have studied the wetting behavior of molten germanium on silica ceramics and amorphous silica coatings in vacuum at a pressure of 1 Pa and a temperature of 1273 K. The results demonstrate that the wetting of rough surfaces of ceramic samples and coatings by liquid Ge is significantly poorer than that of the smooth surface of quartz glass. The contact angle of polished glass is ~100°, and that of the ceramics and coatings increases from 112° to 137° as the total impurity content of the material decreases from 0.120 to 1 × 10–3 wt %. Using experimental contact angle data, we calculated the work of adhesion of molten Ge to the materials studied. Its value for the surface of the ceramics and coatings decreases from 0.45 to 0.20 J/m2 with decreasing impurity content, whereas the work of adhesion to a smooth glass surface is 0.55 J/m2. We have fabricated fused silica test containers coated with high-purity amorphous silica. Using horizontal zone refining, we obtained germanium samples with a carrier concentration difference on the order of 1011 cm–3.

A new technique for estimating the average and total impurity concentrations in samples of high-purity substances

A new technique in which the entire set of impurities in a substance is represented as a set of impurity classes has been developed for estimating the most likely and total concentrations of elemental impurities in samples of high-purity substances. Estimates of the purity of samples with the use of this technique have lower random and systematic errors in comparison with estimates without impurity classification. It has been shown that estimates of the integral characteristics of individual impurity classes in the total set of samples allow one to find the expectation of the total concentration for impurity classes which are represented in particular samples only by detection limits. The results are illustrated by the example of the rare-earth oxide samples in the Exhibition–Collection of Extrapure Substances.

Experimental and Simulation Studies of Electrolyte Flow and Slime Particle Transport in a Pilot Scale Copper Electrorefining Cell

Copper electrorefining tests were conducted in a pilot scale cell made of transparent cell walls, allowing direct observation and microscopic video recording of the electrolyte flow. Fluid flow velocities in the gaps between adjacent anodes and cathodes were measured by analyzing the recorded video using a video analysis and modeling software. Modeling and simulation of copper electrorefining in this cell were performed using COMSOL Multiphysics, a finite element method simulation software. The flow velocity field results from modeling agree reasonably well with the measured electrolyte velocities. The transport of slime particle in electrolyte flow was also simulated and the appearance frequencies of slime particles in the domain within 200 microns from cathode surface at different positions of cathodes were compared with impurity levels in the copper cathodes harvested from experimental tests. The results show good correlation especially with the total concentration of major impurities. Thus the cathodic contamination can be predicted by the slime particle appearance frequency in front of the cathode.

Localization of uranium in radiation-damaged nanoheterogeneous natural zircon

High-uranium natural zircon with signs of hydrothermal (up to 300°C) treatment is studied via transmission electron microscopy, Raman spectroscopy, electron probe microanalysis, and local energy-dispersive analysis performed in situ with a transmission electron microscope. Uranium-based phases are not found in the regions with uranium concentrations of up to 10 wt % that exceed considerably the limit of solubility in synthetic zirconium silicate. Uranium is dissolved in a heterogeneous matrix that is formed as a result of the decomposition of radiation-damaged (a dose of 1017 α-decays/mg) zircon under hydrothermal influence. The matrix incorporates amorphous partially hydrated silicon oxide and nanocrystalline cubic (Zr,Hf)1-y MeyO2 stabilized with metal Me impurities (Y, Ca, Al, Fe; y ≈ 0.04). Cubic zirconium oxide is regarded as the preferred phase for uranium localization, while the total impurity concentration is ~0.13.

Impurity distribution in a magnesium sublimate

Impurity distributions across a magnesium condensate produced by sublimation have been determined experimentally. For most of the impurities, the distributions have a complex shape. The Mn and Ca distributions can be described by a distillation equation. The total impurity concentration in the magnesium condensate increases with increasing distance from the substrate. The average total content of all the impurities detected in the condensate is a factor of 3 lower and that of four specially monitored impurities (Fe, Ni, Cu, and Si) is almost a factor of 4 lower than the corresponding original level.

Accelerated glacier melt on Snow Dome, Mount Olympus, Washington, USA, due to deposition of black carbon and mineral dust from wildfire

AbstractAssessing the potential for black carbon (BC) and dust deposition to reduce albedo and accelerate glacier melt is of interest in Washington because snow and glacier melt are an important source of water resources, and glaciers are retreating. In August 2012 on Snow Dome, Mount Olympus, Washington, we measured snow surface spectral albedo and collected surface snow samples and a 7 m ice core. The snow and ice samples were analyzed for iron (Fe, used as a dust proxy) via inductively coupled plasma sector field mass spectrometry, total impurity content gravimetrically, BC using a single‐particle soot photometer (SP2), and charcoal through microscopy. In the 2012 summer surface snow, BC (54 ± 50 µg/L), Fe (367±236 µg/L) and gravimetric impurity (35 ± 18 mg/L) concentrations were spatially variable, and measured broadband albedo varied between 0.67–0.74. BC and dust concentrations in the ice core 2011 summer horizon were a magnitude higher (BC = 3120 µg/L, Fe = 22000 µg/L, and gravimetric impurity = 1870 mg/L), corresponding to a modeled broadband albedo of 0.45 based on the measured BC and gravimetric impurity concentrations. The Big Hump forest fire is the likely source for the higher concentrations. Modeling constrained by measurements indicates that the all‐sky 12 h daily mean radiative forcings in summer 2012 and 2011 range between 37–53 W m−2 and 112–149 W m−2, respectively, with the greater forcings in 2011 corresponding to a 29–38 mm/d enhancement in snowmelt. The timing of the forest fire impurity deposition is coincident with an increase in observed discharge in the Hoh River, highlighting the potential for BC and dust deposition on glaciers from forest fires to accelerate melt.

Characteristics of a nickel thin film and formation of nickel silicide by using remote plasma atomic layer deposition with Ni( i Pr-DAD)2

In this study, the characteristics of a thin nickel film deposited by using remote plasma atomic layer deposition (RPALD) on a p-type Si substrate and formation of nickel silicide by using rapid thermal annealing were determined. Bis(1,4-di-isopropyl-1,3-diazabutadienyl)nickel, (Ni( i Pr-DAD)2) was used as the Ni precursor and an ammonia plasma was used as a reactant. This was the first attempt to deposit a thin Ni film using by Ni( i Pr-DAD)2 as a precursor for the ALD process. The Ni film that was deposited by using RPALD at a growth rate of around 2.2 Å/cycle at 250°C showed a very low resistivity of 33 μΩ·cm with a total impurity concentration of around 10 at.%. The impurities in the thin film, carbon and nitrogen, were existed in the forms of C–C and C–N bonding states. The potential for removing impurities by comparing of experimental conditions, namely, the process temperature and pressure. The nitrogen impurity could be removed by using thermal desorption during each ALD cycle, and the carbon impurity could be reduced by optimizing the process pressure, which is directly related to the mean free path in the NH3 plasma. After Ni deposition, nickel silicide was formed by rapid thermal annealing (RTA) in a vacuum ambient for 1 minute. Nickel-silicide layers from obtained by used the ALD of Ni and obtained by used of the PVD Ni annealed at temperatures from 500 to 900°C. NiSi obtained by used the ALD of Ni showed better thermal stability due to the contributions of small amounts of carbon and nitrogen in the as-deposited Ni thin film. Degradation of the silicide layer was effectively suppressed by using the ALD of ALD Ni.

Seasonal and elevational variations of black carbon and dust in snow and ice in the Solu-Khumbu, Nepal and estimated radiative forcings

Abstract. Black carbon (BC) and dust deposited on snow and glacier surfaces can reduce the surface albedo, accelerate snow and ice melt, and trigger albedo feedback. Assessing BC and dust concentrations in snow and ice in the Himalaya is of interest because this region borders large BC and dust sources, and seasonal snow and glacier ice in this region are an important source of water resources. Snow and ice samples were collected from crevasse profiles and snow pits at elevations between 5400 and 6400 m a.s.l. from Mera glacier located in the Solu-Khumbu region of Nepal during spring and fall 2009, providing the first observational data of BC concentrations in snow and ice from the southern slope of the Himalaya. The samples were measured for Fe concentrations (used as a dust proxy) via ICP-MS, total impurity content gravimetrically, and BC concentrations using a Single Particle Soot Photometer (SP2). Measured BC concentrations underestimate actual BC concentrations due to changes to the sample during storage and loss of BC particles in the ultrasonic nebulizer; thus, we correct for the underestimated BC mass. BC and Fe concentrations are substantially higher at elevations < 6000 m due to post-depositional processes including melt and sublimation and greater loading in the lower troposphere. Because the largest areal extent of snow and ice resides at elevations < 6000 m, the higher BC and dust concentrations at these elevations can reduce the snow and glacier albedo over large areas, accelerating melt, affecting glacier mass balance and water resources, and contributing to a positive climate forcing. Radiative transfer modeling constrained by measurements at 5400 m at Mera La indicates that BC concentrations in the winter–spring snow/ice horizons are sufficient to reduce albedo by 6–10% relative to clean snow, corresponding to localized instantaneous radiative forcings of 75–120 W m−2. The other bulk impurity concentrations, when treated separately as dust, reduce albedo by 40–42% relative to clean snow and give localized instantaneous radiative forcings of 488 to 525 W m−2. Adding the BC absorption to the other impurities results in additional radiative forcings of 3 W m−2. The BC and Fe concentrations were used to further examine relative absorption of BC and dust. When dust concentrations are high, dust dominates absorption, snow albedo reduction, and radiative forcing, and the impact of BC may be negligible, confirming the radiative transfer modeling. When impurity concentrations are low, the absorption by BC and dust may be comparable; however, due to the low impurity concentrations, albedo reductions are small. While these results suggest that the snow albedo and radiative forcing effect of dust is considerably greater than BC, there are several sources of uncertainty. Further observational studies are needed to address the contribution of BC, dust, and colored organics to albedo reductions and snow and ice melt, and to characterize the time variation of radiative forcing.

Electrochmical Corrosion Behavior of Alloy 600 and SA508Cl.3 in Solutions with Various Sodium-to-Chloride Ratios

The laboratory and field experience data indicate that both IGA and SCC of Alloy 600 nuclear steam generator tube material are minimized at a near neutral pH of the range between 6~8. The neutral pH can be achieved by controlling the molar ratio of the cation to anion impurities dissolved in the crevice to be near one. Tubesheet and tubes are galvanically contacted in the tube to tubesheet crevice region of a steam generator. Therefore, the corrosion behavior of tubesheet material should be considered in the application of the molar ratio control. In addition, since the molar ratio is a simple ratio of the cations to anions, the total concentration of the soluble impurities is not considered.In this paper, the corrosion behaviors of tube and tubesheet material are examined by a electrochemical polarization method in solutions with various sodium-to-chloride ratios at room temperature. The effect of the impurity concentration at a constant sodium-to-chloride ratio is also evaluated. Both the corrosion potentials and corrosion rates of Alloy 600 and SA508Cl.3 were significantly decreased as the sodium-to-chloride ratio increased from 0.1 to 10. The corrosion potential and corrosion rate were not affected by a change of the impurity concentration from 0.011 M to 0.11 M at a constant sodium-to-chloride ratio. The corrosion rate of SA508Cl.3, acting as an anode, was increased by about 2~6 times by a galvanic coupling with Alloy 600.

Purification of Magnesium by Vacuum Distillation and its Analysis

Based on thermodynamic analysis, the degree of the separation between magnesium and impurities under vacuum was estimated in this paper. It demonstrated that it may be feasible to purify crude magnesium by vacuum distillation on experimental scale. The high purity (99.98 % or 3N8, mass fraction) magnesium (Mg) was obtained through vacuum distillation using 96 % Mg as a raw material under 15 Pa. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) was applied for the analysis of the raw material and the distilled magnesium for 6 impurity elements. The results indicated that the low-volatile impurities such as Fe, Cu, Mn, Pb, Ca could be reduced at the stage of 873K for 30min and the reduction of total impurity content from 34600 ppm (1N6) for crude magnesium to 180ppm (3N8) upon condensate. In conclusion, purification of magnesium was carried out in an efficient high-yield vacuum distillation system designed and fabricated for purifying 1N6 indigenous magnesium to 3N8 (99.98%).

Purification of yttrium to 4N5+ purity

Purification of yttrium by vacuum distillation was carried out and the purification process of yttrium was studied. More than 60 metallic impurity elements of input as well as purified Y were analysed using glow discharge mass spectrometry (GDMS) and C, N, O, and S were analysed by interstitial gas analysis (IGA). The analysis confirmed the reduction of total impurity content from <10,202.96 ppmw to <27.45 ppmw. High volatile impurities such as Mg, Ca, Ti, Mn, Zn, Dy, Ho Er and Tm were reduced effectively after the first step carried out at ∼1600 °C for 4–6 h. The crucible impurity W and Ta was drastically reduced in the distilled yttrium at a distillation temperature of ∼1800 °C under a dynamic vacuum of ∼1.5 × 10−4 Pa; meanwhile, C, N, O, and S were decreased to low content, in which O was 75 ppmw. The evaporation rate and mean free path were calculated under the experimental conditions in this paper.

A Quick Lube Oil and Transformer Oil Quality Monitoring Method

A method is developed for quick oil-quality and performance monitoring by simultaneous determination of the oil’s total impurity content based on optical density in the red, green, and blue wavelength ranges, as well as the chemical properties based on the difference in the chromatic ratios and oil color in TCU ( true color units). This method can be used to determine the quality of fresh oil during its production, monitoring the incoming oils before their use in equipment, and make prompt evaluations of the oil’s performance in the course of tribojunction use.

Research on H&lt;sub&gt;2&lt;/sub&gt;S Removal from Yellow Phosphorus Off-Gas through Catalytic-Oxidizing under Low Temperature and Oxygen Content

Research was conducted to illustrate relevant questions about H2S removal from yellow phosphorus off-gas through catalytic-oxidizing method. Following results have been found out. Firstly, Molecule sieve ZMS-5A, activated carbon ZP-1, ZP-2, ZP-3 and ZP-4 were used as carrier to identify their performances on H2S removal, among which ZP-4 was the optimum one. Secondly, among 3 different impregnants tested in experiments, Na2CO3 was the ideal one to be used as active ingredients of catalyst. And 7% was the suitable concentration of Na2CO3 according to experiments. Finally, catalyst made of carrier ZP-4 impregnated with 7% Na2CO3 was assessed comprehensively to investigate its performance on impurity removal of PH3, H2S, SO2, COS, and CS2. After purification total impurity content in yellow phosphorus off-gas was less than 10g/Nm3, which means purified gas can be used as material as mono-carbon chemical industry.

Neutron irradiation of modern KU-1 and KS-4V fused silica

Investigations performed in the late 1990s showed Russian KU-1 and KS-4V fused silica demonstrated the smallest degradation of transmittance among all quartz materials considered for ITER vacuum windows in visible range under neutron and gamma irradiation. Following a ten-year hiatus, production of KU-1 and KS-4V was recently restarted. New manufacturers claim their products meet previous standards and agreed to transfer samples to Kurchatov Institute for radiation testing.Both grades met total impurity content and unirradiated transparency requirements. Samples were irradiated with fast neutrons to fluences of 6×1016 and 1019cm−2. These fluences significantly exceed the expected fluence for ITER vacuum windows. The visible range transmittance of both KU-1 and KS-4V decreased by 3–5% (5–25%) after lower (higher) fluence, respectively. Their transmittance was dramatically reduced in the UV range. In the visible range, the KU-1 material performed slightly better than the KS-4V material.