Sn-doped CdS: A New Intermediate Band Material for Solar Cells

In this paper, the electronic structure and optical properties of CdS doped by Sn with different concentrations were investigated by first principles. The calculation results of electronic structure show that the doping of Sn can produce a deep impurity level band in the band structure of CdS. The calculation results of optical property show that Sn doping can increase the light absorption coefficient and conductivity of CdS. The overall calculation results show that Sn doping can produce stable intermediate band structure and significantly improve the optical property of CdS.

Band structure tuning of g-C3N4 via sulfur doping for broadband near-infrared ultrafast photonic applications

Graphitic carbon nitride (g-C3N4) featuring a stable heptazine ring structure and high polymerization degree, was indexed as a high thermochemical stability material, attracting rising research enthusiasm for diverse applications. However, the poor near-infrared (NIR) optical absorption and resulting limited NIR applications were pronounced for g-C3N4 due to its large bandgap of 2.7 eV. In the present work, sulfur-doping was manifested by first-principles calculations to introduce impurity level and result in anisotropic spin splitting in g-C3N4 for enhancing broadband nonlinear optical characteristics in NIR regime. The modified sulfur-doped g-C3N4 (S-C3N4) exhibited the maximum effective nonlinear absorption coefficient to be −0.82 cm/GW. Pulse duration within hundred nanoseconds was realized with high modulation stability employing S-C3N4 as saturable absorber in Q-switching operations. Moreover, broadband ultrafast photonics properties were successfully demonstrated in constructed ytterbium-doped and erbium-doped fiber lasers, generating highly stable dissipative soliton and traditional soliton mode-locking pulses. The presented S-C3N4 nanomaterial with remarkable nonlinear optical performances might explicitly boost the development and application of g-C3N4 materials in advanced optoelectronic and ultrafast photonic devices.

Ce Filling Limit and Its Influence on Thermoelectric Performance of Fe3CoSb12-Based Skutterudite Grown by a Temperature Gradient Zone Melting Method

CoSb3-based skutterudite is a promising mid-temperature thermoelectric material. However, the high lattice thermal conductivity limits its further application. Filling is one of the most effective methods to reduce the lattice thermal conductivity. In this study, we investigate the Ce filling limit and its influence on thermoelectric properties of p-type Fe3CoSb12-based skutterudites grown by a temperature gradient zone melting (TGZM) method. Crystal structure and composition characterization suggests that a maximum filling fraction of Ce reaches 0.73 in a composition of Ce0.73Fe2.73Co1.18Sb12 prepared by the TGZM method. The Ce filling reduces the carrier concentration to 1.03 × 1020 cm−3 in the Ce1.25Fe3CoSb12, leading to an increased Seebeck coefficient. Density functional theory (DFT) calculation indicates that the Ce-filling introduces an impurity level near the Fermi level. Moreover, the rattling effect of the Ce fillers strengthens the short-wavelength phonon scattering and reduces the lattice thermal conductivity to 0.91 W m−1 K−1. These effects induce a maximum Seebeck coefficient of 168 μV K−1 and a lowest κ of 1.52 W m−1 K−1 at 693 K in the Ce1.25Fe3CoSb12, leading to a peak zT value of 0.65, which is 9 times higher than that of the unfilled Fe3CoSb12.

Improving radioactive contaminant identification through the analysis of delayed coincidences with an $$\alpha $$-spectrometer

In the framework of rare event searches, the identification of radioactive contaminants in ultra-pure samples is a challenging task, because the signal is often at the same level of the instrumental background. This is a rather common situation for $$\alpha $$ α -spectrometers and other detectors used for low-activity measurements. In order to obtain the target sensitivity without extending the data taking live-time, analysis strategies that highlight the presence of the signal sought should be developed. In this paper, we show how to improve the contaminant tagging capability relying on the time-correlation of radioactive decay sequences. We validate the proposed technique by measuring the impurity level of both contaminated and ultra-pure copper samples, demonstrating the potential of this analysis tool in disentangling different background sources and providing an effective way to mitigate their impact in rare event searches.

Opportunities of combinatorial thin film materials design for the sustainable development of magnesium-based alloys

Magnesium-based lightweight structural materials exhibit potential for energy savings. However, the state-of-the-art quest for novel compositions with improved properties through conventional bulk metallurgy is time, energy, and material intensive. Here, the opportunities provided by combinatorial thin film materials design for the sustainable development of magnesium alloys are evaluated. To characterise the impurity level of (Mg,Ca) solid solution thin films within grains and grain boundaries, scanning transmission electron microscopy and atom probe tomography are correlatively employed. It is demonstrated that control of the microstructure enables impurity levels similar to bulk-processed alloys. In order to substantially reduce time, energy, and material requirements for the sustainable development of magnesium alloys, we propose a three-stage materials design strategy: (1) Efficient and systematic investigation of composition-dependent phase formation by combinatorial film growth. (2) Correlation of microstructural features and mechanical properties for selected composition ranges by rapid alloy prototyping. (3) Establishment of synthesis–microstructure–property relationships by conventional bulk metallurgy.

A Review on Metal Impurities in Pharmaceuticals

Sources of metal impurities can from anywhere in drug product as raw material which may produce using metal catalyst, excipients, process materials, Water or any solvent used, manufacturing equipment, environment, packaging materials. So, it leads to metal impurity in high amount present in final drug product that is why it is important to check the impurity level in final drug product or as well as in process also that it should be present in low or acceptable amount. Any Drug product is not completely pure, some amount of metal impurities are always present in pharmaceutical product may cause various toxicity when it will be administered. Thus it is necessary to check impurity level is present at acceptable amount. The present review gives an account of updated information about metal impurities and reviews the regulatory aspects for such metal impurities in drug substance/drug product. In addition the aim of this article is to discuss the currently used different analytical techniques for detection of metals from drug product like spectrophotometry, X – Ray florescence spectrometry, AAS, INAA, ICP – AES, ICP – MS, MP – AES, Laser Ablation – ICP – MS etc which is used for quality control of metal impurities in pharmaceuticals.

Integrated Constructed Wetland (ICW) System a Sustainable Novel Technique for Urban Wastewater Management

The present study focuses on various aspects of Integrated Constructed Wetland System (ICW) systems with reference to its efficiency, and eco-friendliness in the treatment of domesticwastewater. The biological oxygen demand (BOD) impurity level is in the ranged from 383 mgl-1 to 248 mgl-1, chemical oxygen demand (COD)420 mgl-1 to 340 mgl-1, Total Phosphorus (TP) 10.2 mgl-1 to 5 mgl-1 and Total Nitrogen (TN) 18.9 mgl-1 to 14.8 mgl-1 respectively over a period of one year (SRM University). The influent contaminants are degradable in nature especially with high TP and TN concentrations. Six units of Constructed Wetland System (ICW)units are built with uniform dimensions of 2×1× 0.9 m based on EPA and TVA.The wetland plants chosen areTypha Latifolia and Phragmites Australis. Among the wetland units, Typha oriented units are observed to perform better with a reduction efficiency of 87% for BOD, 86% for COD, 70% for TP and 78% for TN proving that Typha Latifoliais a better aquatic plant for overall wastewater treatment. The removal efficiency increases with time and reaches maximum in 192 hrs. To substantiate the experimental study output, Statistical analysis (ANOVA) and multiple regression analysis with normality plot has carried out. It isevident that thepercentage removal of many parameters especially organic parameters over a period of time in treating with different wetland units is highly significant.

Modelling of expected B, C, N and O Lyman-α line intensities emitted from W7-X plasmas and measured by means of the W7-X light impurity monitor system

The “C/O Monitor” for Wendelstein 7-X (W7-X) is a dedicated light impurity XUV spectrometer intended to measure Lyman-α transitions of hydrogen-like ions of four low-Z impurities—boron (4.9 nm), carbon (3.4 nm), nitrogen (2.5 nm) and oxygen (1.9 nm). Since the discussed diagnostic will deliver continuous information about the line intensities, it is crucial to understand the origin of the obtained signals with respect to the experimental plasma conditions (electron temperature and density). This, however, might be difficult because of the broad acceptance angle of the spectrometer and irregular shape of the plasma edge or SOL where the radiation is expected to mostly come from, depending on the plasma temperature. For that reason, numerous analyses assuming various ranges of electron density and temperature profiles of the W7-X plasmas have been performed (assuming corona equilibrium and neglecting impurity transport processes). The aim of this work is to estimate the expected radiant flux and determine the sensitivity of the system on impurity-level changes. It will allow to improve understanding between measured signal and impurity concentration.

Interfacial properties of [Pt/Co/Pt] trilayers probed through magnetometry

The magnetic and interface properties of [Pt/Co/Pt] were investigated. First, the magnetic properties were determined from the magnetic dead layer plots, in which the Co layer was considered as two distinct parts representing different magnetic properties. The two parts with low and high tCo ranges are close to and away from the top interface (Co/Pt), respectively. The part close to the top interface shows a smaller magnetization (M) value and nonlinear behavior. However, the other part shows a higher M value closer to the bulk value and a linear behavior. The nonlinear behavior of the M values of the low tCo range was converted to an impurity level using simple assumptions. The results showed the effect of the top Pt layer on the magnetic properties of the Co layer. The results clearly demonstrate that magnetometry could be utilized as a means to understand the interface quality of magnetic multilayer systems.