Effect Of Impurities Research Articles

Effects of Impurities and Additives on Interactions of Nuclear-Grade Graphite with Molten LiF-NaF-KF

It has been widely acknowledged that the presence of impurities in molten fluoride salt can alter the salt/material interactions. However, the effects of various impurities such as oxides, metal fluorides, reducing impurities, etc., on the behavior of nuclear-grade graphite in molten fluoride salts have not been reported. This study focuses on understanding the effects of various oxidizing and reducing impurities on the wetting and infiltration behavior of molten FLiNaK salt for nuclear-grade IG-110 graphite. Our results suggest that different impurities can cause different effects on nuclear graphite–molten salt interactions, with some impurities leading to significant degradation of the graphite. Our results demonstrate that certain impurities, such as Cr2O3 and CrF3, lead to a limited increase in wetting and infiltration of molten salt into nuclear graphite, while impurities such as Li2O lead to significantly increased wetting and infiltration throughout the cross section of the graphite specimen. Certain impurities, such as Li, can also lead to significant degradation of the graphite in the salt, with the extent of degradation increasing with the increase in the quantity of Li added. Our results also demonstrate that firing of IG-110 graphite at 900°C under a reducing atmosphere made the graphite surface resistant to wetting by molten FLiNaK salt, as compared to the nonfired sample.

Filtration of Grey Water Using Herbs in a Columnar Evaluation

Filtration of Grey Water Using Herbs in a Columnar Evaluation

Electrical conductivity upon sintering of pure Cu produced by material extrusion additive manufacturing: Effects of pore, grain size, and impurity

This study investigates the development of pores and microstructures at each processing step and sintering conditions in the material extrusion additive manufacturing process, examining their correlation with related physical properties. This is achieved by fabricating copper parts using material extrusion (MEX) and examining the primary factors that impact the electrical characteristics of the MEX parts. Initially, the application of solvent debinding to MEX-produced Cu parts effectively removes a portion of the binder, forming printing-pattern–induced pores and ineffectual pore channels. Subsequently, thermal debinding eliminates the remaining binder and promotes neck formation between the Cu particles. The process proceeds to a subsequent sintering step, where even after the final sintering, some pores remain. These pores are categorized as sintering-induced and printing-pattern–induced pores. The relatively large pore size due to the printing pattern is identified as the main reason for reduced density of MEX parts, especially those influenced by the contour pattern. As the sintering progresses, the grain size increases, with the overall grain size and shape becoming uniform during extended sintering periods. Impurities, specifically carbon and oxygen, are detected in the sintered part, and their concentrations rise with longer sintering times. After examining the variation in porosity, grain size, and impurity content with respect to sintering time, it becomes evident that porosity plays a pivotal role in influencing electrical conductivity. Consequently, the densest 48 h sintered sample, with a relative density of 95.5 %, achieves the highest electrical conductivity at 94.6 % IACS. This demonstrates that MEX can be effectively employed to craft complex-shaped Cu parts with outstanding electrical properties. In summary, densification is crucial for enhancing the electrical properties of Cu parts produced through MEX, achieved by minimizing printing-pattern–induced pores, the primary contributor to density reduction. This study is poised to advance the manufacturing of high-performance, intricate Cu components by providing insights into the development and locations of primary pores through detailed microstructural investigations.

ВЛИЯНИЕ ПРИМЕСЕЙ НА ДЕГРАДАЦИЮ СОЕДИНЕНИЙ В СИСТЕМЕ Al – Au

Typical reasons for degradation of micro–welded bimetallic compounds of the aluminum-gold binary system are considered. These types of compounds are often used in the manufacture of semiconductor products (SCPs) and integrated circuits (ICs). Degradation of compounds, revealed during screen tests or during products operating, leads to failures, which dramatically reduces the reliability of electronic equipment (EE). The majority of degradation processes are based on diffusion phenomena, which are mainly determined by temperature, chemical composition and microstructure of metals and alloys. Impurity elements included in the gold coating have a significant effect on the degradation of the wire connections such as crystal contact pads – traverses of package terminals of SCPs. In this regard, it is worth analyzing the effect of various impurities on the diffusion processes and changes in the microstructure of the coating in order to find out the most dangerous chemical elements and determine their role in the degradation of compounds. The paper presents a review of references on the research subject. In the conclusion, the results of analysis in the field of the influence of impurity elements on the degradation of compounds in Al – Au system are summarized, conclusions are drawn about the key role of grain-boundary diffusion on the degradation of micro-welded bimetallic compounds.

Effect of impurities and carrier concentration on conductivity of bilayer graphene double layer system in different dielectric environments

The electronic transport properties of the bilayer graphene double layer (BLGDL) system at [Formula: see text][Formula: see text]K using the Boltzmann transport equation are reported here. The conductivity of the BLGDL system has been calculated with varying parameters as relative carrier concentration [Formula: see text], short-range (point defect) and long-range (Coulomb charge) impurity concentration, relative dielectric constant [Formula: see text] and interlayer distance [Formula: see text]. The maximum conductivity has been achieved in the absence of short-range impurity. The short-range impurity plays a non-trivial meaningful role in high dielectric and high carrier concentration regimes and limits the conductivity. For higher [Formula: see text] and higher [Formula: see text] values, the nature of the conductivity curve turns out to be of a sublinear nature, while in all other cases, it shows a superlinear trend. Suitable selection of relative dielectric constants, relative carrier concentration and interlayer distance helps to improve the conductivity of the BLGDL system. If the dielectric constant of the spacer is higher than the substrate material, the thickness of the spacer material helps remarkably in enhancing conductivity. Moreover, a comparison of BLGDL with our previously reported MLG–MLG double layer graphene system (DLGS) confirms that higher conductivity is achieved in the case of BLG–BLG system compared to DLGS.

Ortho- to para-hydrogen catalytic conversion kinetics

Hydrogen is a widely considered energy storage option. Hydrogen liquefaction allows for a substantial increase in volumetric energy density; the required conversion of ortho-hydrogen (o-H2) to para-hydrogen (p-H2) is however one of several challenges. This conversion requires a catalyst for sufficiently rapid kinetics, however available conversion data is sparse. To this end, a high throughput ortho-hydrogen (o-H2) to para-hydrogen (p-H2) conversion apparatus is detailed. This enables measurements at a controlled temperature of 77 K via the use of in-situ Raman Spectroscopy for quantitative determination of the ortho-para composition. Conversion kinetic data were acquired for a hydrous ferric oxide catalyst. These data were in reasonable agreement with limited existing literature, thus providing some validation for the use of conversion kinetic models, derived from such data, in hydrogen liquefaction design. Kinetic data was acquired using hydrogen provided via electrolysis; the effect of impurity (H2O) carry-over on conversion kinetics is considered.

Analysis of Factors Affecting the Pigging Effect

In order to ensure production and life safety in the process of oil and gas production, it is necessary to regularly perform pigging operations on pipelines. The fluid-solid coupling effect between the pig and pipeline impurities is complex, and theoretical methods are difficult to solve. Related experimental research is costly and experimental data is difficult to obtain. In order to further explore the factors affecting the cleaning effect of pigs in bi-metal composite pipes, this paper introduces fluid-solid coupling and uses the CEL method to establish a fluid-solid coupling model for the pig, pipeline impurities, and pipeline. The cleaning effect of the pipeline impurities is analyzed in terms of the shape, interference fit amount, and speed of the pig.

Revealing the Effects of Impurities among Phosphoric Acid Electrolytes for the Stability of All-Vanadium Redox Flow Batteries

Revealing the Effects of Impurities among Phosphoric Acid Electrolytes for the Stability of All-Vanadium Redox Flow Batteries

Effect of Impurities on the Compatibility of Steels in Supercritical CO2 at 450°–650°C

Abstract Direct-fired supercritical CO2 (sCO2) power cycles are a pathway to low-CO2 fossil energy but contain O2 and H2O in the sCO2 from combustion. The effect of impurities on structural steels was investigated at 450°–650 °C in 30 MPa sCO2. The test matrix included 9 and 12%Cr ferritic-martensitic (FM) steels and conventional and advanced austenitic steels exposed for 1000–2000 h with and without additions of 1%O2 and 0.1%H2O to simulate the cycle after water removal. For FM steels, the mass gains and scale thicknesses were similar with and without impurities with the formation of thick, duplex Fe-rich scales in all cases including the observation that Fe2O3 only formed with 1%O2. For the austenitic steels, higher mass gains were observed at all temperatures with increased formation of Fe-rich oxides when impurities were added. Carbon ingress was assessed by bulk combustion analysis, glow discharge optical emission spectroscopy (GDOES) and measuring postexposure room temperature tensile properties. Bulk C content was strongly increased at 650 °C but not at 450° or 550 °C.

Effects of impurities on stability of TiC, TaC and ZrC particles in tungsten

Titanium carbide (TiC), tantalum carbide (TaC) and zirconium carbide (ZrC) in form of particles are widely added in W to improve its mechanical and anti-irradiation properties. However, TiC, TaC and ZrC particles are decomposed to Ti-C-O, Ta-C-O and Zr-C-O in W, respectively. To understand the micro-mechanisms, we carry out systematical simulations and find that the presence of impurities such as O, N, and P has great influence on the bond length and bond strength of Ti-C, Ta-C and Zr-C in W. The bond lengths of Ti-C, Ta-C and Zr-C are generally increased when O meets Ti-C, Ta-C and Zr-C. The bond strength of O to Ti-C, Ta-C and Zr-C is much larger than that of C to Ti-O, Ta-O and Zr-O. In contrast, N has little effect on the Ti-C bond, but has great influence on the Ta-C bond. P significantly increases Ta-C bond length, while its influence on Zr-C bond is negligible. The kinetics calculations elucidate that the diffusion barriers of C away from TiO are significantly increased by about 1 eV. It is very difficult for C to escape from TiO and ZrO, and it is also extremely difficult for O to escape from TiC, TaC and ZrC. This may be the reason why Ti-C-O, Ta-C-O, and Zr-C-O particles are found in W when TiC TaC and ZrC compounds are dispersed in W.

Exploring the impacts of Li and He impurities in a tungsten matrix: A First-Principles study

The liquid Li coating on the plasma-facingmaterials (PFM) has been suggested and implemented as a viable and efficient solution to overcome the damage of plasma on PFM in Tokamak devices. However, the internal mechanisms and impacts of tungsten-based PFM are not yet fully understood. Here, we demonstrate the effects of the impurities with multiple Li atoms, the co-doped Li and He atoms, and the self-trapping induced by the He8/He12 and LiHe8/LiHe12 clusters on the mechanical properties and melting point of W, with the aid of the optimized structures, the formation energies, the charge density distribution, and the density of states obtained by the first-principles calculations. The bulk, shear, and Young moduli, together with the anisotropy factor and Poisson ratio, are calculated for each structure by using the calculated elastic coefficients to understand the effects of impurities on the mechanical properties of W. The results show that the substitutional site in the W matrix is more likely to be occupied by a single Li impurity atom and the impurity He atoms prefer the octahedral interstitial, at the same time, the additional Li impurity atoms are more likely to be located at tetrahedral interstitial sites. The charge density distributions and density of states exhibit that the bond energies involving the highly doped Li or He atoms decrease, which leads to a substantial decrease of elastic coefficients and then obviously reduces the melting points, and the shear and Young moduli, although the impurity of single Li and the self-trapping of the single He8/He12/LiHe8/LiHe12 clusters can maintain these physical quantities as PFM. It implies that the impurity concentration of Li or Li-He in the W matrix should be strictly controlled in the PFM application. Therefore, the present investigations can provide a helpful guide for developing PFM with tungsten.

Asymmetrical impurity effect of C70:C60 mixture in thick small molecule organic photovoltaic cells

Fullerenes, especially C70 and C60, and their derivatives are popular acceptor materials for many organic semiconductor devices, including organic photovoltaic cells. One of the main impurities in C70 is C60, and intentional mixture of C60 and C70, or their derivatives, which have been utilized for maximizing the performance of organic photovoltaic cells or perovskite solar cells. However, the influence of impurities in C70 on the device characteristics has not been fully clarified when incorporating C70 into organic devices. To further clarify the relationship between the fullerene mixture and impurities, the effect of impurities in fullerenes on thick photovoltaic cells was evaluated, and a strange asymmetrical impurity effect of the C60:C70 mixture was demonstrated by using C70 with various purities as an acceptor material and zinc phthalocyanine (ZnPc) as a donor material. It was found that C60, C78, and C84 impurities in C70 caused carrier recombination during electron transport, but the same effect of the C70 impurity in C60 was much smaller. Additionally, the impurity effect of higher fullerenes on C70 was clearly larger than that of C60. The effect of higher fullerene impurities can be explained by electron trapping due to their deep lowest unoccupied molecular orbital (LUMO) levels. For the small difference of LUMO energy between C70 and C60, however, it is suggested that the shallow trapping of C70 impurities does not largely inhibit the transport of photocarriers by C60, while the low energy barrier of C60 impurities largely inhibits the transport of photocarriers by C70. For clear comparison, the photoelectrical conversion layers were crystallized using co-evaporant induced crystallization. An effective purification method for C70 using sublimation purification, which depends on the C70 concentration in the sublimation source, is also reported.

Effect of natural non-metallic impurities on the electronic structure and optical properties of sphalerite ZnS

Impurity-bearing sphalerite is widely found in nature and plays a vital role in photocatalysis. A systematic theoretical study of the crystal structure, band gap and optical properties of ZnS containing Si, Se and P impurities, respectively, is carried out using density functional theory calculations. The results show that non-metallic atoms in the interstices narrow the ZnS bandgap, improving the electrical conductivity of sphalerite. Analysis of the optical properties reveals that ZnS containing non-metallic impurities produces light absorption at higher energies. Meanwhile, the presence of all three impurities leads to a red shift in the absorption band edge of ZnS, which favors the extension of the light absorption range of sphalerite. The effect of the Si impurity is greater than that of the remaining two impurities, with the highest red shift. This research contributes to the application of sphalerite (ZnS) containing natural impurities in the field of new luminescent materials.

Effect of Impurities on the Formation of End-Group Clusters in Natural Rubber: Phenylalanine Dipeptide as an Impurity Protein

Effect of Impurities on the Formation of End-Group Clusters in Natural Rubber: Phenylalanine Dipeptide as an Impurity Protein

Grain growth of ice doped with soluble impurities

Abstract. The grain size of polycrystalline ice affects key parameters related to the dynamics of ice masses, such as the rheological and dielectric properties of terrestrial ice as well as the ice shells of icy satellites. To investigate the effect of soluble impurities on the grain-growth kinetics of polycrystalline ice, we conducted annealing experiments on polycrystalline ice samples doped with different concentrations of KCl (10−2, 10−3, 10−4 and 10−5 mol L−1) or MgSO4 (10−2 and 10−5 mol L−1). Samples were annealed for a maximum of 100 h at a hydrostatic confining pressure of 20 MPa (corresponding to a depth of about 2 km) and different constant temperatures of 268, 263, 258 and 253 K (corresponding to −5, −10, −15 and −20 °C, respectively). After each experiment, images of a polished sample surface were obtained using an optical microscope equipped with a cold stage. With grain boundaries detected, grains were reconstructed from the images, and an average grain size was determined for each sample. Normal grain growth occurred in all samples. Grain-size data are interpreted using the following grain-growth model: dn-d0n=kt (d: grain size; d0: starting grain size; n: grain-growth exponent; k: growth constant; t: duration). Values of the best-fit grain-growth exponent, n, for all samples range from 2.6 to 6.2, with an average value of 4.7. Pure ice exhibits 3.1 ⩽n⩽ 4.6, with an average value of 3.8. Above the eutectic point, soluble impurities enhance grain growth, as a melt phase is formed, and it could provide a fast diffusion pathway. Below the eutectic point, soluble impurities impede grain growth probably via the formation of salt hydrates that could pin the grain boundaries. Close to the eutectic point, the grain growth of doped ice is similar to pure ice. Natural ice is impure, often containing air bubbles and soluble impurities, and is usually subjected to a hydrostatic pressure. Our data set will provide new insights into the evolution of grain size within and the dynamics of natural ice masses.

Impurity effect on Bogoliubov Fermi surfaces: Analysis based on iron-based superconductors

Impurity effect on Bogoliubov Fermi surfaces: Analysis based on iron-based superconductors

Impurity effects in a one-dimensional spin nematic liquid

Impurity effects in a one-dimensional spin nematic liquid

Monte Carlo simulation of mobility enhancement in multilayer graphene with turbostratic structure

The transport properties of electrons and holes in the multilayer graphene with a turbostratic structure are investigated by calculating the electrostatic potential induced by ionized impurities on the substrate and integrating the potential profile into Monte Carlo simulation. It is shown that the potential fluctuation caused by the impurities decreases exponentially with the distance from the substrate. The decrease in the potential fluctuation almost nullifies the effect of the impurities on the carrier mobility, showing the carriers to move as fast as the case in the suspended graphene. It is also shown that regardless of impurity density, there is an almost one-to-one correspondence between the mobility and the potential fluctuation. Therefore, it is shown that the use of multilayer graphene with a turbostratic structure is a viable approach to diminish the effects of impurities on the transport properties of graphene, even in systems with high impurity density.

Third-order nonlinear optical susceptibility of hydrogenic impurity in Ge/Si0.15Ge0.85 spherical core/shell quantum dots under electric field

In this review, we have investigated theoretically the third-order nonlinear optical susceptibility in Ge/Si0.15Ge0.85 spherical core/shell quantum dots under electric field (EF) for both cases with and without on-center impurity within the framework of the compact-density-matrix (C.D.M). The eigenenergies and their corresponding wave functions of the system are computed by solving the three-dimensional Schrödinger equation using the effective mass approximation (E.M.A) using the variational method (VM). Our computational results show that both the energy levels and the third-order nonlinear optical susceptibility are strongly affected by the quantum dot size, the effects of the hydrogenic impurity, and the electric field intensity.

Full-radius integrated modelling of ASDEX Upgrade L-modes including impurity transport and radiation

An integrated framework that demonstrates multi-species, multi-channel modelling capabilities for the prediction of impurity density profiles and their feedback on the main plasma through radiative cooling and fuel dilution is presented. It combines all presently known theoretical elements in the local description of quasilinear turbulent and neoclassical impurity transport, using the models TGLF-SAT2 and FACIT. These are coupled to the STRAHL code for impurity sources and radiation inside the ASTRA transport solver. The workflow is shown to reproduce experimental results in full-radius L-mode modelling. In particular, a set of ASDEX Upgrade L-modes with differing heating power mixtures and plasma currents are simulated, including boron (B) and tungsten (W) as intrinsic impurities. The increase of predicted confinement with higher current and the reduction of core W peaking with higher central wave heating are demonstrated. Furthermore, a highly radiative L-mode scenario featuring an X-point radiator (XPR) with two intrinsic (B, W) and one seeded argon (Ar) species is simulated, and its measured radiated power and high confinement are recovered by the modelling. The stabilizing effect of impurities on turbulence is analysed and a simple model for the peripheral X-point radiation is introduced. A preliminary full-radius simulation of an H-mode phase of this same discharge, leveraging recent work on the role of the E×B shearing at the edge, shows promising results.