Cu(In,Ga)Se2 films prepared by sputtering with a chalcopyrite Cu(In,Ga)Se2 quaternary alloy and In targets

This study reports the successful preparation of Cu(In,Ga)Se₂ (CIGS) thin film solar cells by magnetron sputtering with a chalcopyrite CIGS quaternary alloy target. Bi-layer Mo films were deposited onto soda lime glass. A CIGS quaternary alloy target was used in combination with a stack indium target for compensating the loss of indium during annealing process. A one-stage annealing process was performed to form CIGS chalcopyrite phase. Experimental results show that the optimal adhesion strength, residual stress, and resistivity were obtained at a thickness ratio of 67% of bi-layer Mo films and a working pressure of 0.13 Pa. The CIGS precursor was layered through selenization at 798 K for 20 min. The stoichiometry ratios of the CIGS film were Cu/(In + Ga) = 0.91 and Ga/(In + Ga) = 0.23, which approached the device-quality stoichiometry ratio (Cu/(In + Ga) <0.95, and Ga/(In + Ga) <0.3). The resistivity of the sample was 11.8 Ωcm, with a carrier concentration of 3.6 × 10¹⁷ cm⁻³ and mobility of 1.45 cm²V⁻¹s⁻¹. The resulting film exhibited p-type conductivity.     

A hybrid damage model for simulating adiabatic shear bands

International Journal of Fracture - Adiabatic shear band (ASB) is one of the most important failure modes under high strain-rate deformation. In this work, we propose a hybrid damage model to...     

The precursor compound of two types of ZnSe magic-sized clusters

Precursor compounds(PCs)link quantum dots(QDs)and magic-sized clusters(MSCs),which is pivotal in the conversion between QDs and MSCs.Here,for the first time,we report the transformation,synthesis,and composition of a type of ZnSe PCs.ZnSe PCs can be directly transformed to two different MSCs with the assistance of octylamine and acetic acid at room temperature.The two types of MSCs exhibit sharp absorption peaks at 299 and 328 nm which are denoted as MSC-299 and MSC-328.In the preparation of ZnSe PCs,diphenylphosphine(DPP)as an additive plays a key role which not only inhibits the thermal decomposition of Zn precursor,but also acts as a reducing agent to reduce the by-products produced in the reaction.The composition was explored by X-ray photoelectron spectroscopy,energy dispersive spectrometer,matrix-assisted laser desorption/ionization time-of-flight mass spectra with ZnSe PC powder appeared as white powder after purifying by toluene(Tol)and methanol(MeOH).The results indicate that the molar ratio of Zn/Se is 2:1 with a molecular of?3,350 Da.Therefore,we propose that the molecular formula of ZnSe PCs is Zn₃₂Se₁₆.In addition,at the molecular level,the covalent bond of Zn-Se is formed in ZnSe PCs.This study offers a deeper understanding of the transformation from PCs to MSCs and for the first time proposes the composition of PCs.Meanwhile,this research provides us with a new understanding of the role of DPP in the synthesis of colloidal semiconductor nanoparticles.     

Engineered Cobalt Single-Atoms@BiFeO3 Heteronanostructures for Highly Efficient Solar Water Oxidation

Efficient charge–carrier separation and their utilization are the key factors in overcoming sluggish four-electron reaction kinetics involved in photocatalytic oxygen evolution. Here, a novel study demonstrates the significance of Na₂S₂O₈ as a sacrificial agent in comparison to AgNO₃. Resultantly, BiFeO₃ (BFO) and titanium doped-oxygen deficient BiFeO₃ (Ti-BFO-R) nanostructures achieve ≈64 and 44.5 times higher O₂ evolution in the presence of Na₂S₂O₈ compared to AgNO₃ as a sacrificial agent, respectively. Furthermore, the presence of Co single atoms (Co-SAs) deposited via immersion method on BFO and Ti-BFO-R nanostructures led to achieving outstanding O₂ evolution at a rate of 16.11 and 23.89 mmol g⁻¹ h⁻¹, respectively, which is 153 and 227.5 times higher compared to BFO (in the presence of AgNO₃), the highest O₂ evolution observed for BFO-based materials to date. The successful deposition of Co-SAs is confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and X-ray absorption near-edge structure (XANES). The charge transfer investigations confirm the significance of Co-SAs on BFO-based photocatalysts for improved charge–carrier separation, transport, and utilization. This novel study validates the excellent role of Na₂S₂O₈ as a sacrificial agent and Co-SAs as a cocatalyst for BFO-based nanostructures for efficient O₂ evolution.     

国有企业过度负债的成因及对策

大部分国企由于长年资金短缺、产权不清、资产质量较差等原因而造成的过度负债问题 ,严重阻碍了国企的进一步发展。如何使国企摆脱债务危机 ,增强其竞争能力是一个极其紧迫的问题。     

含硅芳炔树脂的固化及其复合材料性能

通过溶液法在含硅芳炔树脂(PSA)中加入催化剂乙酰丙酮镍和三苯基膦,制备了碳纤维增强PSA复合材料(T700CF/PSA),研究PSA树脂的热自聚固化和催化固化反应动力学、固化树脂的热性能和复合材料的弯曲性能。结果表明:PSA中加入催化剂可降低其固化温度,初始表观活化能下降,但后期固化表观活化能提高。加入催化剂后的PSA的热稳定性略高于未加催化剂的PSA,800℃氮气氛围中残留率达88%。单向碳纤维T700CF增强PSA基复合材料室温下的弯曲强度为1 805 MPa,弯曲模量为149 GPa,300℃下弯曲强度和弯曲模量的保留率分别为73%和93%,其玻璃化转变温度高于500℃。T700CF增强含催化剂的PSA基复合材料的弯曲模量提高,但室温下弯曲强度略有降低。     

自旋转移力矩磁隧道结的建模与仿真

自旋转移力矩磁隧道结(STT-MTJ)是一种新兴的非易失性存储单元.因为有着掉电后数据不丢失、无限的写次数、与CMOS工艺兼容、不会增加器件面积以及良好的可缩放性等诸如多优点而得到了广泛的研究.但是由于目前的工艺厂商尚未推出相应的模型,研究者难以先期使用该技术进行电路设计.文章介绍了STT-MTJ的工作原理,详细研究了使用Verilog-A对STT-MTJ建模的思路,并在HSPICE中进行了仿真验证,为后续的STT-MTJ研究奠定了基础.     

Role of molecular structure on bioelectrochemical reduction of mononitrophenols from wastewater

The effect of nitro-substituent on mononitrophenol (o-nitrophenol (ONP), m-nitrophenol (MNP) and p-nitrophenol (PNP)) reduction in a bioelectrochemical system (BES) was investigated in this study. The results show that the removal of all three nitrophenols was significantly enhanced with more negative cathode potential and shortened hydraulic retention time in the BESs. Moreover, the reduction of the three nitrophenols followed in the order of ONP > MNP > PNP in the BESs. Both quantum chemical calculation using density function theory and cyclic voltammetry analysis confirmed the reductive sequence of the three nitrophenols. In addition, the acute toxicity of nitrophenol effluent significantly decreased while its biodegradability was enhanced after treatment in the BES. Therefore, the BES technology offers bright prospects for efficient treatment of nitrophenol-containing wastewater.     

Priority setting in maintenance management: a modified multi-attribute approach using analytic hierarchy process

In the current economic climate, budgets for the maintenance of public buildings are unlikely to meet the ever-increasing maintenance needs. Although it is unlikely that this problem can be overcome completely without an injection of further resources, it is possible for government maintenance authorities to improve the situation by ensuring that the best solution in terms of ‘value for money’ is achieved in the planned maintenance programme. A maintenance plan which is based on a rational assessment of priorities and up-to-date knowledge of the condition of the property stock will help to ensure the best use of available resources. Based on the multi-attribute maintenance prioritization model developed by Alan Spedding, Roy Holmes and Qiping Shen at the University of West of England, which is simple in practice and flexible from a management point of view, this paper presents the results of some further research into this area by modifying the original model using an analytical hierarchy process in deciding the weightings of the criteria set out in the prioritization model. This modified model is more quantitative and objective than the original model. The validation of the framework is also discussed.