Local structural characterization of Zn:Cd:Se ternary semiconductors

We have studied the local atomic structure around Zn and Cd, in CdSe, ZnSe, and ordered and disordered Zn_0.5Cd_0.5Se thin films, grown by molecular beam epitaxy (MBE) and atomic layer epitaxy (ALE) using X-ray absorption spectroscopy (XAS). Zn K-shell X-ray absorption fine structure (XAFS) shows that the Zn–Se pair nearest neighbor distance is the same in both ordered and disordered ternary samples. This result shows that the ordered (or disordered growth) does not have a significant effect in the nearest neighbor Zn environment. However, results from K-shell Cd XAFS show that the Cd–Se pair nearest neighbor distance in the Zn_0.5Cd_0.5Se ordered film exhibits a contraction compared to the same pair distance in the disordered Zn_0.5Cd_0.5Se sample and the binary CdSe compound. This suggests that the shortest Zn–Se nearest neighbor distance regulates the Cd–Se nearest neighbor distance in the ternary compounds, when these are grown in an ordered, layer by layer, fashion.     

Selective Recovery of Cadmium,Cobalt, and Nickel from Spent Ni–Cd Batteries Using Adogen® 464 and Mesoporous Silica Derivatives

Spent Ni–Cd batteries are now considered an important source for many valuable metals. The recovery of cadmium, cobalt, and nickel from spent Ni–Cd Batteries has been performed in this study. The optimum leaching process was achieved using 20% H₂SO₄, solid/liquid (S/L) 1/5 at 80 °C for 6 h. The leaching efficiency of Fe, Cd, and Co was nearly 100%, whereas the leaching efficiency of Ni was 95%. The recovery of the concerned elements was attained using successive different separation techniques. Cd(II) ions were extracted by a solvent, namely, Adogen^® 464, and precipitated as CdS with 0.5% Na₂S solution at pH of 1.25 and room temperature. The extraction process corresponded to pseudo-2nd-order. The prepared PTU-MS silica was applied for adsorption of Co(II) ions from aqueous solution, while the desorption process was performed using 0.3 M H₂SO₄. Cobalt was precipitated at pH 9.0 as Co(OH)₂ using NH₄OH. The kinetic and thermodynamic parameters were also investigated. Nickel was directly precipitated at pH 8.25 using a 10% NaOH solution at ambient temperature. FTIR, SEM, and EDX confirm the structure of the products.     

GFAAS法测定LiMn2O4中的Pb和Cd

采用石墨炉原子吸收光谱法(GFAAs)测定锂离子电池正极材料LiMn2O4中杂质Pb和Cd的含量.探讨了HNO2浓度、Pb和Cd的灰化温度和原子化温度、基体改进剂对测定结果的影响.该方法的操作简单,准确度高,Pb的回收率为91.22%～93.75%,Cd的回收率为96.5%～108.6%;精密度好,两种元素测定的相对标准偏差RSD(n=lO)<5%.     

四川盆西平原区裸土扬尘中Pb、Cd化学形态的生物有效性

为探究四川盆西平原区裸土扬尘中Pb、Cd总质量分数与其生物有效性的规律,在构建的"阳离子型污染物土壤表层运移行为研究系统"内进行模拟起尘试验,对土壤样品进行Pb、Cd模拟污染试验,结果表明:试验条件下,四川盆西平原区裸土扬尘颗粒物中Pb、Cd的总质量分数随着粒径的减小而增大,其中Pb的化学形态以碳酸盐结合态为主(44....     

Sputtered Zn(O,S) buffer layers for CIGS solar modules—from lab to pilot production

Sputtering of Zn(O,S) from ZnO/ZnS compound targets has been proven to be a promising buffer layer process for Cd‐free CIGS modules due to easy in‐line integration, low cost and high efficiency on lab scale. In this publication, we report on successful upscaling of the lab process to pilot production. A record aperture efficiency of 13.2% has been reached on a 50 × 120 cm² sized module. Neither a non‐doped ZnO layer nor additional annealing steps are required. Moreover, this very reproducible process yields a standard deviation comparable with that of the CdS base line. In contrast to lab experiments, strong performance gain after light soaking has been observed. The light‐soak‐induced power increase depends on the preparation of the window layer. Accelerated aging tests show high stability of module power. This is confirmed by outdoor testing for 20 months. Copyright © 2017 John Wiley & Sons, Ltd.     

As Doping in (Hg,Cd)Te: An Alternative Point of View

Acceptor doping of many II–VI compound semiconductors has proved problematic and doping of epitaxial mercury cadmium telluride (MCT, Hg_1−x Cd _x Te) with arsenic is no exception. High-temperature (>400°C) anneals followed by a lower temperature mercury-rich vacancy-filling anneal are frequently required to activate the dopant. The model frequently used to explain p-type doping with arsenic invokes an amphoteric nature of group V atoms in the II–VI lattice. This requires that group VI substitution with arsenic only occurs under mercury-rich conditions either during growth or the subsequent annealing and involves site switching of the As. However, there are inconsistencies in the amphoteric model and unexplained experimental observations, including arsenic which is 100% active as grown by metalorganic vapor-phase epitaxy (MOVPE). A new model, based on hydrogen passivation of the arsenic, is therefore proposed.     

Compositional engineering of chemical bath deposited (Zn,Cd)S buffer layers for electrodeposited CuIn(S,Se)2 and coevaporated Cu(In,Ga)Se2 solar cells

A comparative study of chemical bath deposition (CBD) of ZnS, CdS, and a mixture of (Cd,Zn)S buffer layers has been carried out on electrodeposited CuIn(S,Se)₂ (CISSe) and coevaporated Cu(In,Ga)Se₂ (CIGS) absorbers. For an optimal bath composition with the ratio of [Zn]/[Cd] = 25, efficiencies higher than those obtained with CdS and ZnS recipes, both on co‐evaporated CIGS and electrodeposited CISSe, have been obtained independent of the absorber used. In order to better understand the (Cd,Zn)S system and its impact on the increased efficiency of cells, predictions from the solubility diagrams of CdS and ZnS in aqueous medium were made. This analysis was completed by in situ growth studies with varying bath composition by quartz crystal microbalance (QCM). The morphology and composition of the films were studied using scanning electron microscopy (SEM) and X‐ray photoelectron spectra (XPS) techniques. Preliminary XPS studies showed that films are composed of a mixture of CdS and Zn(O,OH) phases and not a pure ternary Cd_{1 − x}Zn_xS compound. The effect of the [Zn]/[Cd] molar ratio on properties of the corresponding CISSe and CIGS solar cells was investigated by current voltage [J(V)] and capacitance voltage [C(V)] characterizations. The origin of optimal results is discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

垂直布里奇曼法生长的Cd0.8 Mn0.2Te单晶体中Te沉淀相分析

Cd1-xMnxTe（CdMnTe,CMT）是制备光学隔离器、太阳能电池、x射线和γ射线探测器的优选材料。本实验采用垂直布里奇曼（VB）法成功地生长出Cd0.8Mn0.2Te单晶体。用JEM-3010型高分辨透射电子显微镜（HRTEM）观察了CMT晶体中的纳米级Te沉淀。选区电子衍射得到了Te沉淀与CMT基体两相的合成电子衍射图。计算出单斜Te沉淀的晶胞参数为：a=0.31nm,b=0.79nm,c=0.47nm,β=92.71°。确定了Te沉淀和CMT基体的取向关系为（0 31）Te//（202）CMT,[100]Te//[111]CMT。最后,对Te沉淀（缺陷）的形成原因进行了分析。     

时效对Mg-Zn-Nd-Zr-Cd合金力学特性的影响

采用光学显微镜、XRD衍射分析仪、SEM扫描电镜、维氏硬度计、透射电子显微镜、万能拉伸试验机等仪器研究时效工艺对合金Mg-3.8Zn-2.8Nd-0.6Zr-0.6Cd力学特性的影响。结果显示,时效后合金强度有较大的提高,伸长率略有下降。采取双级时效90℃×10 h+150℃×8 h热处理,合金的屈服强度与抗拉强度分别达到320 MPa和350 MPa。双级时效热处理时,因为分解产物的数量更多、尺寸更小,因此强化效果要比单级时效的更明显。     

Effect of concentration of cadmium sulfate solution on structural,optical and electric properties of Cd1-xZnxS thin films

Cd1-xZnxS thin films were deposited by chemical bath deposition(CBD)on the glass substrate to study the influence of cadmium sulfate concentration on the structural characteristics of the thin film.The SEM results show that the thin film sur-faces under the cadmium sulfate concentration of 0.005 M exhibit better compactness and uniformity.The distribution dia-grams of thin film elements illustrate the film growth rate changes on the trend of the increase,decrease,and increase with the increase of cadmium sulfate concentration.XRD studies exhibit the crystal structure of the film is the hexagonal phase,and there are obvious diffraction peaks and better crystallinity when the concentration is 0.005 M.Spectrophotometer test results demonstrate that the relationship between zinc content x and optical band gap value Eg can be expressed by the equation Eg(x)=0.59x2+0.69x+2.43.Increasing the zinc content can increase the optical band gap,and the absorbance of the thin film can be improved by decreasing the cadmium sulfate concentration,however,all of them have good transmittance.At a concen-tration of 0.005 M,the thin film has good absorbance in the 300-800 nm range,80％transmittance,and band gap value of 3.24 eV,which is suitable for use as a buffer layer for solar cells.