Increasing Impurity Concentration Research Articles

The Influence of the Distribution Law and Uniformity of a Threshed Mixture with the Working Parameters of a Soybean Threshing Device

Soybean plants cultivated using mulched drip irrigation planting technology have the following characteristics during the harvest period: green stems and leaves, and a high straw/grain ratio. Moreover, the threshing device of a soybean combine harvester is difficult to adapt to, resulting in an increase in the accumulation and unevenness of the threshed mixture. This leads to an increase in impurity content and the loss rate. We conducted a single-factor experiment on a self-developed longitudinal/axial-flow soybean threshing and separation test bench, employing drum speed, feeding rate, and threshing clearance as experimental factors. The influence of the soybean threshing and separation device’s working parameters on the distribution and uniformity of the threshed mixture in the axial and radial directions of the drum was explored through experiments. The results showed that the mass of the threshed mixture and soybean seeds showed a trend of first rapidly increasing and then slowly decreasing in the axial direction of the drum. Additionally, the mass showed a distribution feature of large values on both sides and small values in the middle in the radial direction. A lower drum speed, greater threshing clearance, and a smaller feeding rate make the radial distribution of a threshed mixture more uniform. Based on the combination of the crushing rate and unthreshed rate, the optimal working parameter combination was determined to be as follows: a drum speed of 500 r/min, a feeding rate of 6 kg/s, and a threshing clearance of 25 mm. The findings of this research offer valuable insights for the structural optimization and design enhancement of threshing and cleaning mechanisms within soybean combine harvesters.

Breathing impure plasmas

A theory is presented to describe fluctuation dynamics in magnetized plasmas with impurities. In particular, it is shown that impurities can significantly facilitate an abrupt transient increase of fluctuation amplitude. To demonstrate this, a fluid model is derived to describe how impurities enter fluctuation dynamics. At the linear level, a wave similar to a drift wave can be excited in the presence of impurities. The nonlinear dynamics of this wave is formulated via modulational analysis, and it is demonstrated that drift waves with impurities can develop into a breather, a nonlinear wave that exhibits transient increase of amplitude. Our model indicates that nonlinear breathers become easier to be excited as impurity concentration increases. Breathers transiently increase fluctuation amplitude, and hence may be important to expel impurities. Implications on basic experiments and magnetic fusion are discussed as well.

Characteristics of the incorporation of Yb defect states in CuO:ZnO nanocomposite

Exploring magnetic order in nonferromagnetic substances, such as CuO:ZnO, becomes especially attractive when introducing defect states through nonmagnetic ion doping. In this study, we delved into the impact of Yb doping on the structural, morphological, optical, and magnetic properties of CuO:ZnO. The Yb doped CuO:ZnO was prepared with different Yb concentrations (x = 0.00–20 %) via the temperature-assisted co-precipitation method. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, and vibrating sample magnetometer (VSM) were used to investigate the structural, morphological, optical, and magnetic properties of Yb doped CuO:ZnO nanocomposites.The incorporation of Yb in CuO:ZnO nanocomposites leads to a notable shift of the characteristic XRD peaks of CuO and ZnO to lower angles, accompanied by an increase in the lattice parameters. UV–visible absorption spectroscopy shows an overall decrease in the optical band gap energy of ZnO as the Yb defect level increases. FE-SEM studies revealed the transformation of spherical structures into agglomerated non-spherical structures upon the introduction of Yb ions into CuO:ZnO nanocomposites. According to XPS data, the predominant valences of Yb-doped CuO:ZnO nanocomposites are Zn2+, Cu2+, and Yb3+. One noteworthy observation from the XPS results is that, in comparison to the intensity of OL or Oad peaks, the intensity of OV (Oxygen vacancy) defect peak increases when the Yb impurity concentration increases. Magnetic measurements demonstrated a diamagnetic order in pure ZnO, which converts to a ferromagnetic order with the incorporation of Yb defect states. The ferromagnetic properties of the Yb-doped CuO:ZnO nanocomposite can be ascribed to the exchange interaction of Yb3+ ions with defect states (Oxygen Vacancy) in ZnO and CuO.

Effect of Impurities on Solubility and Metastable Zone Width of Manganese Sulfate Monohydrate

AbstractRecovering manganese from waste batteries is an important issue to promote the development of new energy. Herein, nickel sulfate and cobalt sulfate, representative impurities in waste battery leachate, are selected to examine their influence on the crystallization thermodynamics and crystal nucleation of manganese sulfate monohydrate. This work assessed alterations in solubility and metastable zone width (MSZW) due to the presence of impurities. The results showed a decrease in manganese sulfate monohydrate solubility in water with increasing impurity concentrations of either nickel sulfate or cobalt sulfate. The effects of initial concentration, heating rate, and impurity concentration on MSZW demonstrated a consistent increase in MSZW as these factors increased. The MSZW data are fitted using the self‐consistent Nývlt‐like model and the classical 3D nucleation theory model. The results revealed a general increase in the nucleation rate constant, K, with increasing saturation temperature or decreasing nickel sulfate concentration. Conversely, the solid‐liquid interface energy, γ, generally decreases with increasing saturation temperature or decreasing nickel sulfate concentration. Based on the influence observed on the interface energy, a possible mechanism is proposed that suggests that impurities inhibit crystal nucleation through adsorption.

Controlling Unintentional Defects Enables High‐Efficient Antimony Selenide Solar Cells

AbstractDeep‐level defects in semiconductor materials usually induce carrier trapping and non‐radiative recombination. However, defects caused by unintentional contaminants in antimony selenide (Sb2Se3) solar cells have rarely been reported. Herein, the correlation between defect properties and unintentional impurities in the Sb2Se3 absorber is investigated, which is prepared by injection vapor deposition with Sb2Se3 source purities ranging from 99.9% to 99.9999%. The analysis of deep‐level transient spectra reveals that an increase in impurity concentration does not result in new defect types. Nevertheless, the higher impurity level causes an increase in both the defect density and the capture cross section of the original defect. To address this challenge, defect engineering is developed to regulate the growth of the Sb2Se3 absorber. This strategy completely suppresses deepest defect states E3, a mixture of intrinsic defect (SbSe) and impurity Si related defect. As a result, the carrier lifetime increases significantly from 0.37 to 3.4 ps. This enables to fabricate Sb2Se3 solar cells with a power conversion efficiency of 10.41%. This work uncovers the characteristics of unintentional contaminant‐related defects, and provides a strategy for fabricating highly efficient Sb2Se3 solar cells with low‐purity source materials.

Kinetics of phase separation and aging dynamics of segregating fluid mixtures in the presence of quenched disorder.

Quenched or frozen-in structural disorder is ubiquitous in real experimental systems. Much of the progress is achieved in understanding the phase separation of such systems using the diffusion-driven coarsening in an Ising model with quenched disorder. But there is a paucity of research on the phase-separation kinetics in fluids with quenched disorder. In this paper, we present results from a detailed molecular dynamics simulation, showing the effects of randomly placed localized impurities on the phase separation kinetics of binary fluid mixtures. Two different models are offered for representing the impurities. We observe a dramatic slowing down in the pattern formation with increasing impurity concentration. This sluggish domain growth kinetics follows a power-law with a disorder-dependent exponent. The correlation function and structure factor show a non-Porod behavior, indicating the roughening of the domain interfaces. We have also studied the effect of quenched disorder on the aging dynamics by calculating the two-time order parameter auto correlation function and find that the Fisher and Huse scaling law holds good in the presence of quenched disorder.

Characterization of impurity distribution and composition on the shutter plate for an optical diagnosis in EAST tokamak using laser-induced breakdown spectroscopy

The quantification of impurities in tokamak devices is of great significance as it allows for a better understanding of the plasma performance and the lifetime of plasma-facing components (PFCs). This study focuses on the characterization of the impurity distribution and composition on the surface of a shutter plate for an optical diagnosis in the Experimental Advanced Superconducting Tokamak (EAST) by Laser-Induced Breakdown Spectroscopy (LIBS). The primary impurity elements, including copper (Cu), tungsten (W), molybdenum (Mo), lithium (Li), and Sodium(Na), were identified by analyzing the LIBS spectra obtained from the surface of the shutter plate. The spatial distribution of these impurities on both sides of the plate was investigated. The analysis results indicate an increase in impurity content on the outer surface of the shutter plate as proximity to Last Closed Flux Surface (LCFS), followed by a near-linear decrease with the distance from the LCFS. The results of the inner ring on the inner side facing the glass window show fewer metal impurities than the outer rings on the edge for the inner side of the plate. Moreover, the thickness of the deposition layer was determined by estimating the Average Ablation Rate (AAR) through the measurement by confocal microscopy. In addition, Calibration-Free LIBS method were performed to determine the relative content of impurities. The results of this study provide valuable references for studying the migration and transportation of impurities.

A Simulation Study on Evaluating the Influence of Impurities on Hydrogen Production in Geological Carbon Dioxide Storage

In this study, we examined the effect of CO2 injection into deep saline aquifers, considering impurities present in blue hydrogen production. A fluid model was designed for reservoir conditions with impurity concentrations of 3.5 and 20%. The results showed that methane caused density decreases of 95.16 and 76.16% at 3.5 and 20%, respectively, whereas H2S caused decreases of 99.56 and 98.77%, respectively. Viscosity decreased from 0.045 to 0.037 cp with increasing methane content up to 20%; however, H2S did not affect the viscosity. Notably, CO2 with H2S impacted these properties less than methane. Our simulation model was based on the Gorae-V properties and simulated injections for 10 years, followed by 100 years of monitoring. Compared with the pure CO2 injection, methane reached its maximum pressure after eight years and eleven months at 3.5% and eight years at 20%, whereas H2S reached maximum pressure after nine years and two months and nine years and six months, respectively. These timings affected the amount of CO2 injected. With methane as an impurity, injection efficiency decreased up to 73.16%, whereas with H2S, it decreased up to 81.99% with increasing impurity concentration. The efficiency of CO2 storage in the dissolution and residual traps was analyzed to examine the impact of impurities. The residual trap efficiency consistently decreased with methane but increased with H2S. At 20% concentration, the methane trap exhibited higher efficiency at the end of injection; however, H2S had a higher efficiency at the monitoring endpoint. In carbon capture and storage projects, methane impurities require removal, whereas H2S may not necessitate desulfurization due to its minimal impact on CO2 storage efficiency. Thus, the application of carbon capture and storage (CCS) to CO2 emissions containing H2S as an impurity may enable economically viable operations by reducing additional costs.

Investigation of Defect Formation in Silicon Doped with Silver and Gadolinium Impurities by Raman Scattering Spectroscopy

Silicon doped with gadolinium and silver impurities were studied using a Renishaw InVia Raman spectrometer. Registration and identification of both crystalline and amorphous phase components in the samples was carried out. Some changes are observed in the Raman spectra of gadolinium-doped silicon samples compared to the initial sample. It has been experimentally found that an increase in the silver impurity concentration in gadolinium-doped silicon leads to a smoothing of the Raman spectrum, which indicates the formation of a more perfect crystal structure.

The combined effect of highly variable DC current – Simulated from solar irradiance data – And electrolyte quality on zinc electrowinning

This paper is the second in a series of two papers focusing on the applicability of highly variable direct current (DC) for the production of high quality cathodes by electrowinning. Different current profiles were simulated from solar irradiance data and then applied to electrowinning cell using a precision programmable power supply. The simulated DC current was applied to the zinc electrowinning process, which was chosen as a case study due to its intensive energy consumption. The present work discusses the combined effect of highly variable current with the concentration of magnesium ions (Mg2+) in the zinc sulfate electrolyte. The impact of this impurity is relevant due to the complex mineralogy of the zinc ores available for processing (i.e., magnesium is one of the major elements contained in low-grade silicate ores). The results showed that even over a wide range of applied current densities (highest average value = 697 A m−2; highest peak value = 1486 A m−2), the average values of current efficiency calculated for the process, according to the different types of solar irradiance variability, are comparable. The lowest value (90.3% for intermittent day) could be explained by high amplitude variations in the intensity of the current density, which enhances the hydrogen evolution rate. The average values of current efficiency decreased with increasing impurity concentration in the electrolyte; decreases of 0.8–2.0% units in the average value of current efficiency were calculated at 15 g L−1 Mg2+. At this concentration, an increase of 2.1–6.8% in the average values of specific energy consumption was calculated, which was explained by the observed decrease in current efficiency and a slight increase in the cell voltage due to a decrease in the electrolyte conductivity. The deposits formed in the presence of 15 g L−1 and 30 g L−1 Mg2+ in the electrolyte showed a relatively greater number of pores, which, however, did not cause them to fracture or break during stripping.

Effect of trace impurity elements on the wettability and interfacial reaction between DZ125 alloy and ceramic shell

The effects of impurity elements on the wettability and interfacial reaction between superalloy and ceramic shell were investigated by the sessile-drop method. The wetting angle decreases with the increase of impurity content and the decrease of holding temperature. In addition, the thickness of the interfacial reaction layer increases with the increase of impurity content and the decrease of holding temperature. The adsorption of interfacial active atoms such as O, N and S is the main driving force of the wettability diffusion, which can reduce the surface tension of the alloy melt and enhance the wettability of the solid-liquid interface.

Magneto-electronic and thermopower properties of B, N and Si doped monolayer graphene

Pure graphene is limited by its gapless energy band structure in catalytic reactions that are important for energy conversion applications. However, impurities can create a band gap and improve the electrical and photocatalytic properties of graphene, leading to a wide range of energy-related applications. In this study, the Kubo-Greenwood formula was used to investigate the thermopower properties of monolayer graphene doped with B, N, and Si atoms under various concentrations of impurities and magnetic fields. The impurity concentration was controlled by varying the number of unit cells. The electronic structure of the doped graphene are strongly influenced by the type and concentration of impurities, with a created energy gap that was sensitive to the impurity concentration. Furthermore, applying a magnetic field resulted in subband splitting and band gap reduction for all selected structures, regardless of the impurity type. The thermal properties of the doped structures are dependent on the impurity type, concentration, and magnetic field strength. It was observed that the thermal properties decreased with increasing impurity concentration and were affected by the magnetic field. The thermal properties of the nitrogen-doped structure is higher than those of the boron-doped and silicon-carbide-doped structures. Overall, these findings are significant for developing more efficient energy conversion devices.

The study of structural, electronic, and optical properties of Ti- substituted CaZr1-xTix S3 (x=0.00, 0.25, 0.50, 0.75, and 1.00) for optoelectronic applications: Using GGA and GGA+U

In this study, we examined an orthorhombic phase, CaZr1−xTixS3(x = 0.00, 0.25, 0.50, 0.75, 1.00) (space group Pnma (62)) with B-site Zr substituted by Ti (25%Ti, 50%Ti, 75%Ti) using density functional theory, with the help of a plane wave ultra-soft Pseudopotentials (PW-USPPs) in a generalized gradient approximation (GGA) and with Hubbard onsite correction (DFT + U). The equilibrium state properties such as lattice parameters, unit cell volume, bulk modulus, and its derivative are calculated. The change in concentration of Ti affects the bulk modulus and its derivatives which results in variations in the compressibility and hardness of the material. It is found that CaZr1−xTixS3 with different concentrations of Ti shows a tuned direct band gap located at Γ-symmetry point. The band gap values decrease as impurity concentration increases. The band gap values of CaZr1−xTixS3 (for 0.25, 0.50, 0.75, and 1.00) lie in the optimal energy range (1.0–1.6 eV). Moreover, it is observed that CaZr1−xTixS3(x = 0.00, 0.25, 0.50, 0.75, 1.00) has a good optical response from the visible to ultraviolet energy range. The results predict these materials may be used in solar cell applications and optoelectronic devices.

Interplay between diffusion and magnon-drag thermopower in pure iron and dilute iron alloy nanowire networks

Results of measurements on the thermoelectric power of 45 nm diameter interconnected nanowire networks consisting of pure Fe, dilute FeCu and FeCr alloys and Fe/Cu multilayers are presented. The thermopower values of Fe nanowires are very close to those found in bulk materials, at all temperatures studied between 70 and 320 K. For pure Fe, the diffusion thermopower at room temperature, estimated to be around − 15 upmuV/K from our data, is largely supplanted by the estimated positive magnon-drag contribution, close to 30 upmuV/K. In dilute FeCu and FeCr alloys, the magnon-drag thermopower is found to decrease with increasing impurity concentration to about 10 upmuV/K at 10% impurity content. While the diffusion thermopower is almost unchanged in FeCu nanowire networks compared to pure Fe, it is strongly reduced in FeCr nanowires due to pronounced changes in the density of states of the majority spin electrons. Measurements performed on Fe(7 nm)/Cu(10 nm) multilayer nanowires indicate a dominant contribution of charge carrier diffusion to the thermopower, as previously found in other magnetic multilayers, and a cancellation of the magnon-drag effect. The magneto-resistance and magneto-Seebeck effects measured on Fe/Cu multilayer nanowires allow the estimation of the spin-dependent Seebeck coefficient in Fe, which is about − 7.6 upmuV/K at ambient temperature.

Lutetium-Doped ZnO to Improve Photovoltaic Performance: A First-Principles Study

We investigated the effect of different impurity concentrations of lutetium (Lu)-doped ZnO on its optoelectronic properties utilizing the first principles based on density functional theory. The findings show that 1.85 at.% Lu-ZnO has the smallest lattice distortion and the impurity formation energy is less than zero, with the likelihood of chemical preparation. Analysis of electrical properties revealed that the conductivity of Lu-doped ZnO decreases with increasing impurity concentration and all show n-type semiconductors. Moreover, the spectral data suggested that the transmittivity increases with increasing doping concentration, and optical properties were extremely sensitive to the impurity concentration in the visible region. The current findings will greatly broaden the application of ZnO in photovoltaic devices.

Quantum effects in the low-temperature thermal expansion of fullerite C60 doped with a 4He impurity

The thermal expansion of fullerite C60 doped with a 4He impurity at T ∼2 K has been investigated by the method of low temperature precision dilatometry in the interval T = 2.2−24 K. The character and the derived values of the thermal expansion coefficients were strongly dependent on the concentration of the 4He impurity in fullerite. In the interval T = 2.2−5 K the thermal expansion of the 4Hex−C60 system is negative, which is attributed to the tunnel movement of the 4He atoms in the cavity system of the C60 crystal lattice and at the crystallite surface. The contribution of this process to the thermal expansion decreases as the impurity (4He) concentration increases and the probability of 4He tunneling between the crystal lattice cavities and the impurity-free areas of the grain surface diminishes. In the temperature interval T = 4.5−24 K the thermal expansion of the 4Hex−C60 system is influenced predominantly by the mutual transformations of different orientation glass modifications of fullerite. Owing to their tunnel character the transformations make a negative contribution to the process of thermal expansion entailing a hysteresis and other anomalies observed in this temperature interval. The intensity of the processes provoked by the tunneling-encouraged phase transformations of the orientational glasses of C60 increases with the 4He concentration in fullerite.

Research of redistribution of impurities in silicon wafers under influence of white light pulses

Research of redistribution of impurities in silicon wafers under influence of white light pulses. / A. B. Gerasimov, G. D. Chiradze. / Nano Studies. – 2020. – # 20. – pp. 95-98. – rus. The aim of this work is to study the redistribution of impurities in silicon wafers caused by exposure to white light pulses. There are investigated silicon wafers of n-type conductivity doped with phosphorus with resistivity of 0.5 Ohm·cm and thickness of 500 μm (KEF–0.5). The samples surface was treated according to the 14th class of cleanliness. In order to remove natural oxide, before exposure to light and before each measurement the samples were processed in aqueous solution of HF in ratio of 1:50 for 50 s. Microhardness was measured by the indentation method. It was found that in the region, where the microhardness decreases in comparison with the initial sample, the impurity concentration increases, while in the region of increasing microhardness the concentration decreases. With an increase in the duration of light pulses and their number, the effect of redistribution of impurity atoms increases. Moreover, the effect of redistribution is greater near the surface, from which the illumination took place. Fig. 2, Ref. 7.

Surface modification of recycled polymers in comparison to virgin polymers using Ar/O2 plasma etching

AbstractLow‐pressure plasma etching of a recycled polyethylene terephthalate (PET) film is studied in comparison to virgin PET and polypropylene (PP) using a capacitively coupled radio frequency (RF) plasma reactor. Recycled polymers are distinguished by increased impurity content and weakened mechanical properties, both affecting plasma etching and adhesion processes. Mild plasma conditions have been selected to maintain the material bulk properties of the polymers. The etch rates and the morphology of the polymer samples were thus determined at floating potential compared with etching at the RF electrode for varying argon/oxygen gas mixtures, etching duration, and sample size. Thermoanalytical and X‐ray techniques were used to characterize the polymer before and after the plasma etching treatment. Finally, adhesive‐tape peel tests proved that excellent adhesion of silver coatings can also be achieved on a plasma‐treated recycled PET film.

Crystallization and grain growth in impurity-doped colloidal polycrystals

Alloying has long been used to control the properties of crystalline materials. However, the microscopic details of the effects of adding impurities remains poorly understood, as directly imaging these processes is challenging in atomic systems. Here we study how crystallization and grain growth are impacted by impurities in a quenched monolayer of a colloidal polycrystal. The rates of crystallization are unaffected by the impurity concentration and well described by the Johnson-Mehl-Avrami-Kolmogorov model. However, with an increased impurity concentration, more of the system becomes frustrated and does not crystallize. The rate of grain growth is significantly slowed down due to grain boundary pinning. Nevertheless, the evolution of the polycrystalline structure is well described by a single correlation length, and dynamic scaling applies up to relatively large impurity concentrations. Finally, we develop a simple model accounting for both crystallization and grain growth to describe the time evolution of the correlation length, and we find good agreement with our experimental data at all impurity concentrations. Our results shed new light on the interplay between crystallization, grain growth and the presence of impurities in impurity-doped polycrystalline systems.

InPNBi/InP heterostructures for optoelectronic applications: A k‧p investigation

We have thoroughly investigated various potential possibilities of exploiting InPNBi for electronic and optical applications considering the 16-band k∙p perturbation Hamiltonian. Taking into account strain-relaxed condition for InPNBi with InP by maintaining a specific ratio (0.92) between N and Bi, we have figured out the electronic bandgap as 0.782 eV, equivalent wavelength of ∼1.58 μm, and spin–orbit coupling energy (ΔSO) as 0.173 eV of InP0.904N0.046Bi0.05 respectively. An extensive range of electronic bandgaps and corresponding operating wavelengths spanning from 1.42 eV (∼0.9 μm) to 0.401 eV (∼3 μm) are observed for N and Bi impurity concentrations up to 10% and 9.2%, respectively. Incorporation of both Bi and N impurity consequences to reduction in electron effective mass of InPNBi (0.065 m0) by ∼1.2 times with respect to the host InP (0.079m0), which boosts the optical properties of InPNBi/InP quantum confined heterostructures. Increasing impurity concentration and the applied electric field leads to red shift in the gain spectra and reduction in peak amplitude, which facilitates the likelihood of realizing InPNBi/InP for the optical modulators, 1 eV solar cells, and infrared detectors.