Total Impurity Content Research Articles

Anatase to rutile transition in TiO2 thin films: Role of tantalum and oxygen

The present study discusses the optimal solubility limit of tantalum in anatase TiO2 thin films (dopant solubility limit) and its effect on crystal structure transformation to the rutile phase. The study also focuses on the role of lattice oxygen in this structural phase transition. The detailed chemical composition, constitution, and phase of these sputter-deposited thin films are correlated with their electrical and optical properties to understand the disparity between total impurity concentration in these films and actual impurity substitution into the host lattice sites (dopant content). Reduced oxygen vacancies from the oxygen lattice sites and/or Ta substitution in Ti lattice sites are found to hinder the anatase to rutile phase transformation in TiO2 thin films. Our experimental data indicates the solubility limit of Ta being < 5 at% in TiO2. Similar behavior is seen when Ta is replaced with Nb in TiO2 thin films. Moreover, an increased oxygen and/or impurity concentration is found to lead to impurity-rich-oxides in these films, degrading the electrical conductivity.

Automated preparation of Actinium-225 with accelerator-based production from irradiated natural thorium targets

Towards the goal of accelerator-based 225Ac production from proton and nitrogen irradiated natural thorium targets, this work hereby presents a self-designed preparation system that allows for continuous operation with improved multi-column ion-exchange method. The system with advantageous features validated the feasibility of the automatic separation and purification of actinium from hundreds of impurity nuclides. Through automated experiments with multiple targets, the recovery yield and the radionuclide purity of final 225Ac products was stabilized to be around 63 % and 92 % ∼ 96 %, respectively. The total content of stable impurities is measured to be less than 2.4 μg in the final actinium product. The radioactivity levels of 226Ac and 227Ac in the product are evaluated over time. Based on the results of evaluation, the optimal time to start separation is determined to be around the 10th day after the end of bombardment. Additionally, the 225Ac-PSMA-617 compound was synthesized with the 225Ac product that meets the requirement of nuclear medicine.

Structural characteristics and properties of heat-resistant nickel β-alloys produced via the centrifugal SHS-casting method

Employing centrifugal self-propagating high-temperature synthesis (SHS) metallurgy, complemented by advanced metallurgical processes such as vacuum induction melting (VIM) and vacuum arc remelting (VAR), yielded the alloy formulation denoted as base–2.5Mo–1.5Re–1.5Ta–0.2Ti. This study investigates the effects of various technological modes and additional metallurgical treatments on the alloy's impurity and non-metallic inclusion content, structural characteristics, mechanical behavior under compression, and its oxidation mechanisms and kinetics when exposed to temperatures of 1150 °C for 30 h. With increasing centrifugal acceleration, the proportion of non-metallic inclusions (number of points) drops from 5 to 1–2 points. The best combination mechanical properties, including σucs = 1640 ± 20 MPa, σys = 1518 ± 10 MPa, and residual deformation were observed in alloys processed under conditions of increased gravitational force (g = 50). Within a centrifugal force range of g = 20÷300, the composition of the synthesis products aligned with the theoretical expectations. The total content of impurities is 0.15 ± 0.02 %, with a decrease in gas impurities–oxygen and nitrogen levels reduced to 0.018 % and 0.0011 %, respectively. The structural analysis of the alloys revealed the presence of globular and streaked inclusions of a chromium-based solid solution embedded within the matrix. Inclusions with thickness of 2–8 μm are present in the intergranular space: (Cr)Ni,Mo,Co, (Cr)Mo,Re and (Cr)Re,Mo. The formation of the Ni(Al,Ti) phase at grain boundaries was identified, contributing to an enhancement in plastic resistance and overall strength of the alloy. Oxidation mechanisms varied across different processing modes, with the size of structural components significantly influencing oxidation kinetics. The weight gain observed in SHS samples was 70 ± 10 g/m2 with oxidation predominantly occurring along the NiAl interphase boundaries and penetrating into the depth of the sample. TEM facilitated the identification of phases enriched with Ti microadditions, reducing the levels of dissolved nitrogen and oxygen within the intermetallic phase to a combined weight percentage (ΣO,N) of 0.0223 wt.%.

Textures and chemical compositions of muscovite and quartz: Implications for granite-hosted high-purity quartz mineralization and exploration in South China

High-purity quartz (HPQ) has extremely low total impurity content (<20 ppm, IOTA CG, a HPQ standard of Unimin) and is indispensable to many high-tech optoelectronic industries. Whilst the controlling factors for the granite-hosted HPQ formation are yet to be well resolved, it is generally considered to be related to temperature and pressure, and/or specific purification processes. Here, we analyzed the chemical compositions of quartz and muscovite from various HPQ occurrences in South China. The results indicate that the F content in muscovite and Ti content in quartz provide useful indicators for exploring and characterizing the granite-hosted HPQ. More specifically, we found that granites containing muscovite with ≤ 0.100 wt% F have the potential to form 4 N5-grade (SiO2 ≥ 99.995 wt%) HPQ, whereas those with 0.1–1 wt% F have the capacity to generate 3 N- (SiO2 ≥ 99.900 wt%) to 4 N5-grade HPQ. The ideal quartz crystallization temperature (titanium-in-quartz geothermometer (TitaniQ)) to generate 4 N- (SiO2 ≥ 99.990 wt%) grade HPQ is 420 to 490 °C. Higher F content in the granitic melt, which implies higher volatile content, would lower the magma solidus and contribute to the incorporation of impurities such as lattice-bound Ti-Al and fluid inclusions. We propose that in-situ analysis of muscovite and quartz supports rapid assessment of the metallogenic potential of granite-hosted HPQ.

Development of a Purity Certified Reference Material for Vinyl Acetate.

Vinyl acetate is a restricted substance in food products. The quantification of the organic impurities in vinyl acetate is a major problem due to its activity, instability, and volatility. In this paper, while using the mass balance method to determine the purity of vinyl acetate, an improved method was established for the determination of the content of three impurities in vinyl acetate reference material, and the GC-FID peak area normalization for vinyl acetate was calibrated. The three trace organic impurities were identified by gas chromatography tandem high-resolution mass spectrometry to be methyl acetate, ethyl acetate, and vinyl propionate. The content and relative correction factors for the three organic impurities were measured. The purity of vinyl acetate determined by the mass balance method was 99.90% with an expanded uncertainty of 0.30%, and the total content of organic impurities was 0.08% with a relative correction factor of 1.23%. The vinyl acetate reference material has been approved as a national certified reference material in China as GBW (E) 062710.

Investigation of Effects of Sulfuric Acid in Single Wafer Cleaning Process Using Isopropyl Alcohol

Isopropyl alcohol (IPA) was used in the drying process to remove the contamination after the wet cleaning process. Regardless of the types of chemical solutions, the IPA is more strictly controlled because it is used. However, when the IPA was exposed to low acid concentration, the IPA polymers were generated to the di-isopropyl ether, isopropyl acetate, and di-isopropoxy methane. And the pH of IPA rapidly changed by about 1.99 in ppm level concentration. Generated IPA polymers were adsorbed on the wafer surface. These polymers can occur defects, and the probability increases as the concentration increases. Scanning mobility particle sizer (SMPS) measurement system can be measured the impurity in IPA solution. The total impurity concentration was increased by the concentration of H2SO4 with the same results in both gas chromatography mass spectrometry (GCMS) and time of flight secondary ion mass spectrometry (ToF-SIMS). SMPS results can be correlated with the concentration of impurities. In this paper, IPA polymers were defined by acid contamination, and these polymers have affected the Si wafer surface. In addition, the SMPS measurement system was introduced for the detection of impurities in IPA solutions.

Purification of the Al2Cu intermetallic compound via zone melting crystallization technique

The widespread interest in intermetallic compounds has driven the development of their structures and properties, as well as their applications as alternative structural and potentially functional materials. As more and more intermetallic compounds with complex compositions enter the application market, their performance improvement and sustainable recycling face many challenges, where the influence of impurities plays a crucial role. Here, we proposed the direct purification of intermetallic compounds by fractional crystallization and verified for the first time the feasibility and effectiveness of zone melting for the purification of intermetallic Al2Cu. After ten passes of zone melting, results showed no separation of Al and Cu, the major components of Al2Cu. Further analyses demonstrated the homogeneity and remelting stability of Al2Cu before and after zone melting. In addition, the total impurity concentrations at the front and the end of cast Al2Cu bars decreased with increasing number of passes, respectively. After ten passes of zone melting, Al2Cu bar with an initial purity of 3N exhibited higher refining efficiency than those with an initial purity of 4N. Among all impurities, the distribution coefficients of Fe, Si, Zn, and Ti were obviously less than unity (k < 1). Whereas the impurities Ca, Mg and Mn showed behaviors of distribution coefficients less than and/or close to unity.

Oxide unlocking electron beam melting to separate boron for impurities co-removal of metallurgical grade silicon

Removing stubborn B from Si efficiently and simplifying the purification process are critical challenges that must be addressed in the manufacture of solar grade silicon (SoG-Si) via metallurgical routes. Herein, B is flexibly coupled with other impurities separation procedure, so that metallurgical grade silicon (MG-Si) is purified through simplified electron beam melting (EBM) unlocked by a few oxides (0.1 wt%). EBM fulfills three functions including promotion of oxidation, evaporation of impurities, and induction of directional solidification, giving high-temperature field, high vacuum field, and intense melt convection, which not only ensures the smooth process of B oxidation but also favors the co-removal of other impurities, obtaining high purity Si. As a result, purified Si ingot exhibits a low content of B (from 12.76 ppmw to 2.92 ppmw), and the total content of major impurities is reduced from 1217.24 ppmw to 5.66 ppmw. Significantly, pure SiO2 could more readily access the high-temperature region of Si melt during EBM, offering distinct advantages for the oxidation gas phase separation of B. This work provides an efficient and robust method for expanding ideas of B removal and simplifying metallurgical routes.

Chemical Composition and Microstructure Characterization of High Purity CuMn Alloy for Integrated Circuit

High purity copper and copper alloy targets are the key supporting materials for the interconnection of integrated circuits in advanced processes. In this article, the chemical composition and microstructure of Cu-0.6wt%Mn alloy were characterized by means of Glow Discharge Mass Spectrometry, Inductive Coupled Plasma Emission Spectrometer, Optical Microscope and Scanning Electron Microscope. The results show that the total impurity content for Cu-0.69wt%Mn alloy is less than 1 ppm. The three key impurities contents of Ag and Fe and Si could meet the requirement of electronic materials for integrated circuits by use of high purity raw material and appropriate melting and casting methods. Mn content at different positions along the diameter direction fluctuates slightly between 0.66~0.72 wt%, and completely distributed uniformly in the Cu matrix without any trace of aggregation. Due to the influence of raw materials and casting technology, defects such as porosity and carbon inclusion are easy to appear in as-cast microstructure. Therefore, it is necessary to develop new casting mould and casting processing to improve the quality of ingots.

Application of Liquid Smoke from Rubber Wood Clone PB-340 as Latex Coagulant and Preservation of Natural Rubber Coagulum

The utilization of rubber wood waste in the form of liquid smoke has the potential to overcome environmental problems caused by the industry. Therefore, this study aimed to determine the potential of liquid smoke from rubberwood clone PB 340 to be used as a coagulant and preservative. Rubber wood waste was processed into liquid smoke using the pyrolysis method with a temperature of 400°C. Determination of the composition of liquid smoke was carried out using gas chromatography-mass spectrometry (GC-MS) analysis. The results showed that the rubber wood clone PB 340 contained 57.78% cellulose, 12.16% hemicellulose, and 19.01% lignin. Furthermore, volatile analysis with GC-MS showed that liquid smoke from rubber wood clone PB 340 contained 58 organic compounds. Some compounds in liquid smoke were phenols, furans, furfurals, acetic acid, and cyclopentene. The product was then tested for its performance as a latex coagulant at several concentrations of 5%, 10%, 15%, 20%, and 25% v/v, as well as storage time of 1, 7, and 14 days. The treated latex samples that had turned into coagulums were examined for their sheet quality parameters, including initial plasticity (P0), plasticity retention index (PRI), total volatile compounds, impurity, and ash content. The outcomes from all comparisons of pure liquid smoke concentrations and storage time of up to 14 days of the coagulum samples showed that in the initial plasticity value (P0), the plasticity retention index (PRI), volatile matter, ash content, and dirt content had met the applied Standard Indonesian Rubber (SIR).

Assessment of Gold-Bearing Quartz Vein as a Potential High-Purity Quartz Resource: Evidence from Mineralogy, Geochemistry, and Technological Purification

High-purity quartz (HPQ) is an important material widely used in many high-tech industries. It is a product processed from pure natural quartz raw materials, so selecting suitable quartz raw material is the key to successfully processing HPQ. Hydrothermal quartz vein is one of the most likely raw materials to be purified into HPQ because of its high SiO2 content. This study focuses on the evaluation of HPQ raw material potential of the two gold-bearing quartz vein tailing resources in Chibougamau (CBG) and Tianjingshan (TJS). Petrography and the contents of impurity elements in the two vein quartz samples before and after processing were studied by optical microscope, SEM, Raman spectrometry, XRD, LA-ICP-MS, and bulk solution ICP-OES. Petrographic results reveal that major impurities in quartz are feldspar, mica, iron compounds, ankerite, rutile, silicate melt, and fluid inclusions. LA-ICP-MS analysis result shows that the SiO2 contents are between 99.953–99.971 wt.% in CBG raw quartz and 99.969–99.976 wt.% in TJS raw quartz, respectively, with very low contents of impurity elements, except for Ca. Bulk solution ICP-OES analysis demonstrates that the CBG processed quartz sand has total impurity contents of 56.8 µg·g−1, with 13.1 µg·g−1 Al and 6.6 µg·g−1 Ti, and the TJS processed quartz sand has the total impurity contents of 85.2 µg·g−1 with 29.4 µg·g−1 Al and 6.1 µg·g−1 Ti. Both the contents of Al and Ti fit with the lattice-bound criteria for HPQ. These results, for most of the impurities, are likely hosted by silicate melt, fluid, and mineral inclusions, indicating that these two hydrothermal raw vein quartz samples can be upgraded to HPQ after processing by more advanced methods. Therefore, the CBG and TJS quartz vein deposits would be considered as potential future resources for HPQ to realize efficient recovery and utilization of tailings resources and to improve mine economic benefits.

Определение летучих органических примесей в виски методом газовой хромато-масс-спектрометрии

Alcoholic beverages are complex multicomponent objects. Their quality and safety control is a serious analytical task that requires new, more accurate instrumental methods, e.g., chromatography-mass spectrometry. &#x0D; The research involved domestic and foreign whiskey, other alcoholic beverages, and 40% water-alcohol model solutions. The analytical studies were carried out on a Maestro 7820A gas chromatograph GC with an Agilent Technologies 5975 Series MCD mass selective detector, a G4513A autosampler, and a high polarity FFAP capillary column.&#x0D; The research revealed the optimal parameters of chromatographic separation and mass spectrometric detection. The relative measurement error remained below 25% in the range of 1.0–10 mg/dm3 and 18% in the range of 10–500 mg/dm3. These modes were used to study the composition of the volatile organic impurities. The largest proportion of the total volatile impurities was 34.84–58.08% isoamylol, 17.31–26.76% acetic acid, and 12.50–21.28% isobutanol. Other chemical compounds were not so abundant: 0.34–0.86% isoamyl acetate, 0.13–0.39% 1-butanol, 0.03–0.06% 1-pentanol, 0.40–11.20% ethyl lactate, 0.16–2.74% ethyl caprylate, 1.40–6.44% furfural, 0.18–14.60% ethyl caprate, 0.74–2.97% ethyl laurate, and 1.75–2.39% 2-phenylethanol. The maximal total content of volatile organic impurities was 2040.30 mg/dm3: it was registered in apple samogon. The minimal total content of volatile organic impurities was 392.16 mg/dm3 in the unaged rum distillate sample.&#x0D; The new method proved highly accurate in determining the qualitative and quantitative composition of twelve volatile consumable components in whiskey. The procedure took 17 min; it can be applied to mass concentrations of volatile impurities in such alcoholic beverages as grape-brandy, rum, tequila, brandy, samogon, rum, and various distillates.

Combined ultrasound-microwave assisted synthesis of aripiprazole: Process optimization using RSM-ANN

The current work demonstrates combined microwave and ultrasonic assisted synthesis of aripiprazole (ARZ) drug from carbostyril intermediate with piperazine moiety in the presence of a mixture of a green medium. The traditional cooking (TC) technique is time-consuming (≥ 16.45 h), accounts for a significant number of contaminants (≥ 2.63%), and has the drawback of additional repetitive purification stages. The intensification tool simultaneous microwave-ultrasonic irradiation has been employed to overcome these challenges. Response surface methodology (RSM), along with central composite design (CCD), was used to assess the impact of different process parameters on process yield (ϒc) and total impurity content (ὶ). A consistent process yield (≥ 91%) with less total impurity content (≤ 1.45%) was obtained at the optimum condition of reactant mole ratio (1:1), base mole ratio (2.4:1), reaction temperature (85°C) and process time (188 min). Among the exercised numerical tools, a neural network was found to be more precise than RSM for the current system. The synthesis of ARZ followed a second-order kinetic model. The activation energy was found to be 79.61 kJ/mol. Eventually, the qualitative analysis shows a good resemblance between the synthesized products obtained by these two techniques.

Machine-learning-assisted multi-objective optimization in vertical zone refining of ultra-high purity indium

Optimization of processing parameters cannot rely on the trial-and-error method for the production of ultra-high purity metals owing to the complexity of indium raw material and multi-pass processing procedure. A multi-objective optimization strategy was proposed to optimize the process parameters for vertical zone refining of 7N-grade ultra-high purity indium (In) by using machine learning (ML). Firstly, classification models were established for certain impurities (Si, S, Fe, Zn, Ni, Cu and As). In these models, the Synthetic Minority Over-sampling Technique (SMOTE) was introduced to overcome the sample imbalance problem of the experimental dataset. The accuracy of these classification models reached above 0.9. Secondly, a ridge regression model was built to predict the total impurity content in the product. The root mean square error (RMSE) was 0.023, the Pearson correlation coefficient (r) was 0.91, and R-squared (R2) value was 0.79. Using these models, high-throughput virtual screening was performed to conduct vertical zone-refining experiments, which in turn validated the reliability of the models. Feature analysis by Shapley additive explanations (SHAP) revealed that the total impurity content in the final product strongly depended on the content of Ni and Sn impurities in the 6N-grade indium raw material and on the velocity parameter of the 2rd through 4th zone passes (V2). A lower V2 is favorable for eliminating impurities from indium raw material with total impurity content ranging from 0.2 ppm to 0.4 ppm.

Intensification of ethyl alcohol technology due to multienzyme composition

The effect of the complex enzyme preparation Bruzaym BGX on the viscosity of rye kneading was studied. The dynamics of glucose accumulation in the wort is shown, as well as the possibility of reducing the dosage of glucoamylase when using a multi-enzyme complex at the stage of water-heat treatment. The effect of the enzyme complex on the fermentation kinetics of rye wort was studied. It was found that the use of a multienzyme complex at the stage of water-heat treatment allows one to increase the glucose content in the wort by 34.7 %, compared with the control. This increases the yield of alcohol by 1.4 decalitres/t of conditional starch, reduces the duration of fermentation to 50 – 52 hours and reduces the total content of impurities in the mature brew by 10%.

Spatial Distribution of Unique Biological Communities and Their Control Over Surface Reflectivity of the Stanley Glacier, Uganda

Diverse microbes have been revealed to live in glaciers worldwide, but only a few biological studies were dedicated to glaciers in tropical Africa. These glaciers are shrinking rapidly and are expected to disappear shortly. In this study, we carried out biological and glaciological field observations on Stanley Glacier, the largest remaining glacier in the Rwenzori Mountains, Uganda, Africa. Microbial aggregates ranging from micrometer to centimeter in size were found on the glacier surface and contained moss and various types of Chlorophyta, among which a new endemic species of green alga. Concentrations of total impurities on the glacier surface, including microbial aggregates, varied spatially and decreased as altitude increased. The large microbial aggregates (larger than 4 cm in diameter) were found only at the glacier surface near the terminus and side margins, where the surface was less frequently covered with snow. It is also shown that the total organic matter on the glacier surface is determined by the timing of snow cover, which affects the quantity of solar radiation reaching the glacier ice surface. Furthermore, the total impurity content was negatively correlated with surface reflectivity, revealing their potential role in albedo reduction at the glacier surface through positive feedback between enhanced meltwater and increased biological growth.

Development of a combined solution of pyrimidine nucleotides with vitamin B6

Pyrimidine nucleotides, namely uridine monophosphate and cytidine monophosphate, play an important role in the cellular metabolism of nerve fibers. The combination of these nucleotides with pyridoxine hydrochloride (vitamin В6) in one dosage form will allow us to fully implement the strategy of the complex neurotropic pharmacotherapy in neuropathies of various origins. To develop a stable solution, an important step at the stage of the composition development is to study the compatibility of active substances (active pharmaceutical ingredients - APIs) in solution. Samples of binary solutions and solutions containing all active substances were prepared and examined. The API interaction was determined by various parameters – changes in color, transparency, рН, the total impurity content, etc. Based on a comprehensive study of the processes of the API dissolution the optimal pH limits of the solution required for the stable existence of a combination of substances with different pH values of the medium have been substantiated and experimentally confirmed. As a result of the research, the optimal pH value of the solution recommended is 4.0-4.8. In the composition of substances the amount of water can be in an adsorbed or crystallized, or combined form. This fact should be taken into account in order to correctly calculate the actual amounts of initial ingredients when preparing the solution. The nature of the water component of APIs was clarified when studying the phase composition of samples on a powder diffractometer. The studies conducted have allowed us to determine the directions of further research for developing the composition of an injection drug. This research is in choosing the optimal buffer system and excipients-antioxidants.

Use of dilatometer to screen refractory raw materials

AbstractSudden shortage of a particular raw material due to freight disruptions, competitive market, and COVID restrictions have frequently forced the refractory industry to rapidly develop alternative formulations using available low‐cost materials. These alternative ingredients might cursorily appear to have similar total impurity content, but the presence of certain impurity combinations depending on the refractory type can produce more fluid liquid phase at high temperature, thereby drastically reducing hot strength. Undetected by the commonly used X‐ray fluorescence (XRF) analysis, the low‐cost material might differ in mineral‐phase content, whose phase transformations during firing might create excessive expansion producing warpage of the refractory along with a high porosity reducing strength and corrosion resistance. Finally, those cheap raw materials might have similar sieve analysis to that of the standard ingredient but might have much lower tapped density, which would introduce detrimental porosity into the resulting refractory. Hence, time‐consuming trials are often performed. Dilatometer studies on pressed or cast samples in a single test can identify reaction temperatures of spinel or mullite formation, which expand during firing, along with the amount of expansion and exact times at which firing needs to be done. It can also compare relative shrinkage due to liquid‐phase formation among impure raw materials like recycled grogs or low‐grade ores. Finally, dilatometric step scan is shown as a fast technique to prepare in‐house, low‐cost reactive spinel powder, which can also work for mullite.

Recovery of Te for the scrap of Bi2Te3-based alloys by vacuum metallurgy

Every year a large amount of scrap can be produced from the Bi2Te3-based alloys when processing. A clean, new vacuum distillation method is proposed to purify Te from the scrap of Bi2Te3-based alloys. In this work, the saturated vapor pressure, distillation rate and separation coefficient of each metal element in Bi2Te3-based alloys are theoretically analyzed. The effects of distillation temperature and time on the volatilization and condensation behavior of elements are studied under the dynamic vacuum of 0.1 Pa. According to the research results, a multi-stage distillation method is proposed, and Te was purified from 41.53% to 98.88% while the total impurity content was reduced to 1.12% through this procedure. Moreover, Te of the scrap of Bi2Te3-based alloys can be separated and recovered effectively via this three-step vacuum distillation. The results lay the foundation for the industrial purification of Te and provide a low-cost, simple and green recycling process of thermoelectric scrap, which has important practical significance.

THE REFINING OF TITANIUM BY CRUCIBLELESS ZONE MELTING METHOD

The physical substantiation of titanium refining by crucibleless electron beam zone melting (ZM) method in vacuum was presented. Calculations of the equilibrium, limiting and effective distribution coefficients for impurity elements in the base metal were carried out. The refining of titanium was studied experimentally, and samples with a purity of 99.92 wt.% were received. The total content of impurities was reduced by a factor of 1.5 (from 0.12 to 0.08 wt.%). The concentration of interstitial impurities was significantly reduced (oxygen – by 1.3; carbon – by 2; nitrogen – by 2.5 times). The structure and microhardness were investigated.