Different Concentrations Of Impurities Research Articles

Significant Hall–Petch effect in micro-nanocrystalline electroplated copper controlled by SPS concentration

Electroplated Cu has been extensively applied in advanced electronic packaging, and its mechanical properties are critical for reliability. In this study, Cu foils fabricated through electroplating with various bis-(3-sulfopropyl) disulfide (SPS) concentrations are examined using tensile tests. The SPS concentration affects the grain size of the electroplated Cu foils, resulting in different mechanical properties. A significant Hall–Petch effect, {sigma }_{y} = 197.4 + 0.12{d}^{frac{-1}{2}}, is demonstrated for the electroplated Cu foils. The different concentrations of impurities identified through time-of-flight secondary ion mass spectrometry correspond to the different grain sizes, determining the transgranular and intergranular fracture during the tensile test. The results demonstrate that the SPS concentration controlling the microstructures of the electroplated Cu results in a Hall–Petch effect on the mechanical properties of the electroplated Cu foils.

Effect of pH on Pharmaceutical Ingredients / Drugs / Chemicals

The word excipient is derived from the Latin excipere meaning to except, which is simply explained as other than. Pharmaceutical excipients are basically everything other than the active pharmaceutical ingredient. Ideally, excipients should be inert, however, recent reports of adverse reactions have suggested otherwise. Pharmaceutical excipients are substances other than the active pharmaceutical ingredient (API) that have been appropriately evaluated for safety and are intentionally included in a drug delivery system. Solubility, which defines the liquid /solid equilibrium, is a key parameter to control a crystallization process. As the API is a weak acid (pKa = 3.7), its solubility increases with the pH. On the basis of the experimental curve of solubility, a model was defined to fit the evolution of the solubility as a function of pH. In the case of this compound, studies revealed a weak influence of the temperature in comparison with the pH. So, the solubility of the compound is slightly impacted by the temperature. Some experiments were carried out in order to compare the solubility of the API, at the same pH and temperature, for different concentrations of impurities found in the process. The results revealed a solubility increase in presence of acetic acid and a high solubility decrease in presence of sodium chloride. By carrying out experiments on common ions salts, the anion chloride Cl− has been identified as the cause of the solubility decrease. Keywords: Solubility, API, Impurity, Ph

Оценка селективности обратноосмотических мембран при разделении бинарных растворов хлоридов натрия

Manufacturers of reverse osmosis filter membranes provide their products with computer programs that allow for technological evaluation calculations for solutions with different concentrations of impurities. The description of the programs does not include the computer methods and algorithms which are necessary for calculating traffic flows. Consequently, it is not possible to evaluate the selectivity of the reversely osmotic stages of membranes. The development of computer algorithms and techniques that would evaluate the operation of reverse osmosis plants taking into account external and internal parameters is an important practical task. The article discusses reverse osmosis processes in installations with membrane filtration associated with the purification of water enriched with salt. The physical mechanisms of purification are considered, and it is shown that the difference between the working and osmotic pressures plays a leading role in this mechanism. Purification of water enriched with salt by a membrane is accompanied by diffusive flows of the salt component of the solution. The reverse osmosis process is simulated, in which salt water is fed under high pressure into a chamber with a membrane permeable only to water. The permeate outlet flow is low-pressure pure water, and the retentate flow is salt-enriched water. The initial parameters are set, namely, the pressure drop on the membrane, the mass fraction of salt at the inlet and the flow rate. An increase in the mixing rate reduces the concentration polarization on the inlet side of the membrane and increases the flow of water through the membrane.

Fading estimation of SOL-GEL α-Al2O3 detectors

The OSL and the TL techniques are used in several fields of radiation dosimetry. The dosimeters are affected by a signal loss in the time between the irradiation and readout (fading). This undesirable characteristic can cause an underestimation of the irradiation dose. The fading estimation of SOL-GEL α-Al2O3 with several different concentrations of impurities is reported. The thermal fading and the light-induced fading of the SOL-GEL α-Al2O3 detectors were estimated. Furthermore, the exponential equations used to interpolate the experimental results were presented.

Theoretical Aspect of Physical Phenomena in Inorganic Photovoltaic Cells. Electrical Modeling and Numerical Simulation

This work is based on the development of a theoretical model describing the drift and diffusion transport of photogenerated charge carriers and the impact of space charge on this transport in relation to the different physical phenomena characterizing the photovoltaic conversion in an inorganic silicon-based cell. In a second step, we used a numerical solution of the transport differential equations based on the Runge-Kutta algorithm in the framework of the finite difference method, This led us to an electrical model of the photovoltaic cell and of the photo-generated currents by RLC circuit equipped with a diode modeling the direction of electron and hole transport and allowed us to study the relations between the optical and electrical properties of the cell, as well as the influence of the different concentrations of impurities used for the n-type and p-type doping of the silicon on the properties of absorption of the light photons, the spectral response as well as the conductivity, the open-circuit potential and the short-circuit current.

Study of lateral growth regions in ammonothermal c-plane GaN

Lateral growth in the a-direction is an effective way to expand the size of crystal in basic ammonothermal GaN growth. Cathodoluminescence image of cross section clearly revealed several different regions along a-direction. Stress distributions and optical properties were investigated among these different regions by Raman spectroscopy and photoluminescence spectroscopy, respectively. TOF-SIMS mapping showed the spatial distribution of O, H, Si and C impurities in lateral growth regions. Our results indicate that there is small stress variation among the interfaces. Different concentration of impurities incorporated in these regions, especially O impurity, which can significantly increase the free carrier concentration. Fairly low concentration and uniform distribution of C impurity indicated that YL band in PL spectra is not closely related to carbon impurity or a complex involving carbon. Based on the above data, the evolution process of lateral crystal growth is deduced.

SOL-GEL α-Al2O3 samples: Analysis of the TL kinetics

The analysis of the thermoluminiscence (TL) kinetics parameters of SOL-GEL α-Al2O3 with several different concentrations of impurities prepared through the solgel process is reported. A TL glow curve measured at 0.2 K/s after beta irradiation to 0.5 Gy revealed one peak at approximately 447 K. TL spectra were acquired and showed luminescent emission bands around 420 nm and 750 nm. The activation energies, the frequency factors, and the kinetic order involved in the TL emission were evaluated using the maximum peak temperature response, the peak shape of the TL glow curve, the TL glow curve area, and the glow curve fitting methods. The order of kinetics of the peak was evaluated as first order using TM dependence on the radiation dose. The (TM–Tstop) technique was used for determining the number of peaks in the glow curve. The activation energies obtained are in agreement with all the applied methods. The activation energy calculated by various methods varied from 0.885 ± 0.008 eV to 1.05 ± 0.10 eV. The frequency factor determined by all methods was of the order of 109 s−1. The dosimetric peak is affected by thermal quenching. The following thermal quenching parameters were estimated: the activation energy of the thermal quenching W = 1.05 ± 0.15 eV and the constant C = 8.27 × 1010 s−1. The trapping parameters of SOL-GEL α-Al2O3 detectors are reported in the present work for the first time.

Effects of carbon impurity on the ignition of deuterium-tritium targets under the relativistic shock waves

One of the main concerns about the ignition and burn of deuterium-tritium (DT) plasma is the negative effect of impurities that can get into the thermonuclear fuel during target compression on the ignition of an inertial confinement fusion (ICF) target. So, the ignition condition of the spherical DT plasma of the ICF target in the presence of high-density carbon impurities at an arbitrary concentration is found. The ignition criterion of nuclear fusion plasmas is investigated using a two-temperature model derived from a common model. The ignition criterion is described by a surface in the three-dimensional space. This surface is defined by the electron and ion temperatures, Te and Ti, and the plasma density times the hot spot dimension, ρ·R, for different concentrations of impurities. In this paper, a two-temperature laser induced shock wave is used. We found that one needs a laser intensity of 7.5 × 1021 W/cm2, a pulse duration of 1ps, and an energy of 0.44 kJ that induces a compression of κ = 4 to ignite a pure DT pre-compressed target at about 500 g/cm3. Given the constant intensity of the laser, the increase in the carbon impurity concentration increases the alpha energy deposition in the igniter zone; on the other hand, the temperature of the igniter zone decreases as a result of high losses of power densities, so that for impurity values of more than 20%, practically no hot spots are formed.

SOL-GEL α-Al2O3 detectors: TL and OSL response to beta radiation beams

The dosimetric properties of the SOL-GEL α-Al2O3 detectors with several different concentrations of impurities were studied in beta radiation beams. For the characterization of the detectors, the TL and OSL techniques were used. A TL spectrum was acquired. The detectors showed adequate OSL and TL dosimetric characteristics, such as good reproducibility, a glow curve with the peak at ~230 °C at 5 °C/s of heating rate, adequate OSL decay curve, good linearity of response and high phosphor sensitivity. A thermal treatment study was also performed. Moreover, the calibration factors and the lower detection limits were determined for beta radiation. These characteristics indicate the suitability of SOL-GEL α-Al2O3 detectors for the establishment of a transfer system or alternative/complementary method for beta radiation dosimetry.

DFT study of the role of N- and B-doping on structural, elastic and electronic properties of α-, β- and γ-graphyne

The effects of N and B substitutional doping on α-, β- and γ-graphyne structures have been systematically considered by means of spin-polarized DFT calculations. The study is focused on describing the main changes that doping of sp2-and sp-C atoms produces on structural, elastic and electronic properties. Thus, the presence of N impurities contracts the carbon lattice increasing the in-plane stiffness whereas B impurities expand the lattice reducing the in-plane stiffness with respect to pure graphynes. This fact leads to harder materials or softer materials depending on doping with N or B atoms, respectively. Moreover, N and B atoms are n- and p-type dopants, respectively, that modify significantly the electronic structure of these materials. The different concentration of impurities in the lattice may lead to semiconductor-to-metal transitions, to the opening of a band gap, or to the appearance of new Dirac points (DPs) in the electronic structure, depending on the different parity of electrons or holes introduced per unit cell. The intrinsic physical properties of graphynes along with the possibility of tuning them by substitutional doping could extend their applicability as separation membranes, in transistor electronics, optoelectronics, among others.

Deciphering the Role of Impurities in Methylammonium Iodide and Their Impact on the Performance of Perovskite Solar Cells

Solution‐based perovskite solar cell fabrication typically involves rather complex processing sequences to yield highest performance. While most studies concentrate on the exploration of processing conditions, the purity levels of common perovskite precursor solutions have been investigated and a number of impurities that are critically important toward controlling the crystallization of perovskites are found. In this study, an in‐depth chemical study of the possible impurities formed during CH3NH3I preparation is presented and their relevance on solar cell processing is revealed. A primary consideration is the chemical transformation of hypophosphorous acid, which plays the role of the stabilizer for HI. The detrimental role of the impurities is best demonstrated by comparing perovskite solar cell devices fabricated from impurity‐free precursors versus precursors containing different concentrations of impurities. Most interestingly, it is revealed that a certain concentration of impurities is detrimental to the growth of large‐grained crystals. PbHPO3 nanoparticles, which are formed after hypophosphorous acid transformation, actually cause crystal domain growth through serving as a nucleation center. This study gives valuable insight into the rate determining steps of perovskite crystal growth and further provides the basis for developing reliable and reproducible high‐performance recipes for perovskite solar cell processing.

Effects of B and Al on tensile strengths and electronic structure of CuZr: A first-principles study

We investigate effects of B or Al impurities on structure and tensile strengths of CuZr by using first-principles density functional calculations. The calculations indicate that B or Al atoms doped on Zr atoms are energies favorable structure. We present stress–strain relationships for Cu–Zr–X (X = B, Al) systems along chosen directions. Both B and lower concentrations of Al decrease the tensile strengths, although there exists stronger covalent bonds between X and nearest neighbor Cu/Zr of Cu–Zr–X than that of CuZr, and plasticity in these systems can be triggered by electronic instabilities under tension. CuZr0.5Al0.5 possesses larger tensile strengths than CuZr, and we analyze mechanism of different tensile strengths for different concentrations of impurities by Mulliken overlap populations. All calculations show that the effects of B or Al impurities on tensile strengths of CuZr are quite composition-dependent.

Ballistic transport properties in pristine/doped/pristine graphene junctions

We investigate the ballistic electron transport in a monolayer graphene with configurational averaged impurities, located between two clean graphene leads. It is shown that the electron transmission are strongly dependent on the concentration of impurities and the incident energy. In turn, the conductance computed using the Landauer formalism shows a similar behavior to those found in experimental works as a function of the applied voltage for different concentrations of impurities in the limit of low temperatures. In the limit of zero bias voltage, the conductance shows a minimum value which reduces to zero for high concentration of impurities which disentangle graphene sublattices. These results can be very helpful for exploring the tunneling mechanism of electrons through doped thermodynamically stable graphene.

Purification of artemisinin from quercetin by anti-solvent crystallization

In the present work, anti-solvent crystallization of artemisinin from four different organic solvents (methanol, ethanol, acetonitrile, and acetone) was studied. Water was used as anti-solvent. The effect of an impurity (quercetin) on the performance of anti-solvent crystallization of artemisinin was investigated. The fundamental process data such as solubility of artemisinin in pure organic solvents and their binary mixtures with varying composition water were measured at room temperature. The solubility of quercetin was measured only in pure organic solvents at room temperature. Anti-solvent crystallization experiments were designed based on the fundamental process data determined. Firstly, the anti-solvent crystallization of artemisinin without impurity was performed from all four organic solvents and then the experiments were repeated with addition of an impurity (quercetin) while keeping all other process parameters constant. Two different concentrations of impurity, i.e., 10% and 50% of its solubility, in the respective organic solvents at room temperature were used. The effect of impurity on performance of anti-solvent crystallization was evaluated by comparing the yield and purity of the artemisinin obtained with those in the absence of impurity. Results of the present work demonstrated that the presence of quercetin in the solution does not affect the final yield of artemisinin from the solution of each of four organic solvents used. However, the purity of artemisinin crystals were reduced when quercetin concentration was 50% of its solubility in all solvents studied.

Temperature dependence of laser-induced damage threshold in silica glass

The laser-induced damage thresholds in silica glasses at different temperature conditions (123 K – 473 K) by Nd:YAG laser fundamental (wavelength 1064 nm) and third harmonic (wavelength 355 nm) 4 ns of pulses were measured. In the results, the damage thresholds increased at low temperature. At 1064 nm, the temperature dependence became strong by the concentration of impurities. However, at 355 nm, the temperature dependences of almost sample were almost the same for different concentration of impurities.

Influence of pH, Temperature and Impurities on the Solubility of an Active Pharmaceutical Ingredient (API)

Solubility, which defines the liquid /solid equilibrium, is a key parameter to control a crystallization process. This work is focused on the effects of pH, temperature and impurities on the aqueous solubility of an Active Pharmaceutical Ingredient (API).As the API is a weak acid (pKa = 3.7), its solubility increases with the pH. On the basis of the experimental curve of solubility, a model was defined to fit the evolution of the solubility as a function of pH. In the case of this compound, studies revealed a weak influence of the temperature in comparison with the pH. So, the solubility of the compound is slightly impacted by the temperature.Some experiments were carried out in order to compare the solubility of the API, at the same pH and temperature, for different concentrations of impurities found in the process. The results revealed a solubility increase in presence of acetic acid and a high solubility decrease in presence of sodium chloride. By carrying out experiments on common ions salts, the anion chloride Cl- has been identified as the cause of the solubility decrease.

Study of the response to minimum ionising particles of microstrip detectors made with float zone and magnetic Czochralski silicon after neutron irradiation

The use of various silicon substrates to improve the radiation hardness of tracker detectors for high energy physics experiments has been investigated for several years. Single crystal silicon grown with different methods has different concentrations of impurities (mainly O and C). It has been found that relatively high concentrations of particular impurities in the silicon crystal can affect the degradation of some of the detector electrical properties as a function of the radiation dose. When high resistivity Czochralski (Cz) silicon became available after refinement of the Cz method for growing single crystal silicon ingots, the new material (magnetic Cz, MCz) was tested for radiation hardness with promising results obtained with simple pad diodes. A crucial measurement for evaluating the radiation tolerance of the detectors is though the response to minimum ionising particles (MIPs) of finely segmented devices. To this purpose, miniature microstrip sensors made on n and p-type MCz substrates have been produced and compared to identical ones made on n and p-type standard floating zone (FZ) detector grade silicon. The study has been performed evaluating the signal induced by beta electrons from a 90Sr source and measured with an LHC speed (40 MHz clock) analogue electronics readout. The comparison of MCz and FZ n and p-type detectors has been carried out after several doses of neutron irradiation (up to 1×10 15 n cm −2).

Distortion effects and clustering of isotopic impurities in solid molecularpara-hydrogen from variational Monte Carlo simulations with shadow wave functions

We employed a fully optimized Shadow Wave Function (SWF) in combination with Variational Monte Carlo techniques to investigate the properties of HD molecules and molecular ortho-deuterium (o-D_2) in bulk solid para-hydrogen (p-H_2). Calculations were performed for different concentrations of impurities ranging from about 1% to 25% at the equilibrium density for the para-hydrogen crystal. By computing the excess energy both for clustered and isolated impurities we tried to determine a limit for the solubility of HD and o-D_2 in p-H_2.

Peculiarities of a Solid-State Synthesis of Multiferroic Polycrystalline BiFeO3

Studies of a BiFeO3 synthesis were performed to identify reasons for the appearance of secondary phases, the Bi25FeO39- and Bi2Fe4O9-type phases, in the reaction product. X-ray diffraction and microstructural analyses, performed on samples with different concentrations of impurities, showed that the impurities in the starting material crucially influence the phase composition of the reaction product. A fraction of the generated secondary phases strongly depends on the nature and concentration of the impurities. The experimental results can be explained by the theoretical consideration of ternary phase relations between Bi2O3, Fe2O3, and an impurity oxide. Single-phase polycrystalline BiFeO3 was synthesized from ultrapure starting oxides. To avoid using the expensive ultrapure oxides, techniques for reducing the fraction of the secondary phases in the reaction products were developed.

Energetic Topography in Adsorption onto Heterogeneous Surfaces

The adsorption of gases onto heterogeneous surfaces has been reviewed, highlighting models capable of taking energetic topography effects into account. The basic ideas are contained in the fundamental Generalized Gaussian Model (GGM) developed to represent mobile adsorption onto heterogeneous surfaces at low coverage, where the energetic topography is considered through an adsorptive energy distribution with a spatial correlation function. Adsorbate molecules interact amongst them via Lennard-Jones interactions. Model predictions have been compared to Monte Carlo simulations of adsorption onto heterogeneous solids obtained by doping a pure crystalline solid with different concentrations of impurities. Energetic topography effects were shown to be important, being predicted correctly by the model at low coverage. In addition, a simplified patchwise model was also considered. The adsorption of particles with nearest-neighbour attractive and repulsive interactions was studied using Monte Carlo simulation on bivariant surfaces characterized by patches of weak and strong adsorbing sites of size “i”. Patches were considered to have either a square or a strip geometry, arranged either in a deterministic ordered structure or in a random way. Quantities have been identified which scale obeying power laws as a function of the scale length “l”. The consequences of this finding for the determination of the energetic topography of a surface from adsorption measurements were discussed.