水热法制备ZnS微球及其生长机理研究

以硝酸锌和硫脲为原料,乙二胺四乙酸二钠(Na2EDTA)为螯合剂,用水热法制备了ZnS微球。用扫描电子显微镜(SEM)对产物的形貌进行了表征,结果表明反应温度以及反应pH对产物粒径大小、表面形貌有很大影响。当反应温度为180℃、pH值为9,反应时间为12h时,所制备的产物约为500nm的球状颗粒。     

Monitoring ZnS Precipitation: Estimation,Error Analysis and Experiment Design

Abstract

A mass balance model of total soluble sulfide and free zinc with a second-order reaction term is theoretically able to reconstruct the zinc effluent concentration and the kinetic parameter (k). However, under real conditions this model predicts the zinc effluent concentration four orders of magnitude higher than the measured ones. The applied error analysis, based on linearization of the model followed by first-order variance propagation, showed that the accuracy of several of the input variables (flows and influent concentrations) jeopardized the estimation of the Zn concentration in the effluent, which is a phenomenon expected for every fast reaction with low product concentration. In order to overcome the inaccuracy issue, an “apparent solubility product” as a function of pS (11-20 König , J. ; Keesman , K.J. ; Veeken , A. ; Lens , P.N.L. ( 2006 ) Dynamic Modelling and Process Control of ZnS Precipitation . Separation Science and Technology , 41 ( 6 ): 1025 – 1042 . Dochain , D. ( 2003 ) State and parameter estimation in chemical and biochemical processes: a tutorial . Journal of Process Control , 13 ( 8 ): 801 – 818 . Del Villar , R.G. ; Thibault , J. ; Del Villar , R. ( 1996 ) Development of a softsensor for particle size monitoring . Minerals Engineering , 9 ( 1 ): 55 – 72 . Zamprogna , E. ; Barolo , M. ; Seborg , D.E. ( 2005 ) Optimal selection of soft sensor inputs for batch distillation columns using principal component analysis . Journal of Process Control , 15 ( 1 ): 39 – 52 . de Brauwere , A. ; De Ridder , F. ; Elskens , M. ; Schoukens , J. ; Pintelon , R. ; Baeyens , W. ( 2005 ) Refined parameter and uncertainty estimation when both variables are subject to error. Case study: estimation of Si consumption and regeneration rates in a marine environment . Journal of Marine Systems , 55 ( 3–4 ): 205 – 221 . Vojinovic , Z. (2007) A complementary modelling approach to manage uncertainty of computationally expensive models. Water Science and Technology , 56 (8): 1–9. Luther III , G.W. ; Rickard , D.T. ; Theberge , S.M. ; Olroyd , A. ( 1996 ) Determination of Metal (Bi)Sulfide Stability Constants of Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ by Voltammetric Methods . Environmental Science & Technology , 30 ( 2 ): 671 – 679 . Luther III , G.W. ; Theberge , S.M. ; Rickard , D.T. ( 1999 ) Evidence for aqueous clusters as intermediates during zinc sulfide formation . Geochimica et Cosmochimica Acta , 63 ( 19–20 ): 3159 – 3169 . Yongsiri , C. ; Vollertsen , J. ; Rasmussen , M. ; Hvitved-Jacobsen , T. ( 2004 ) Air-water transfer of hydrogen sulfide:- an approach for application in sewer networks . Water Environment Research , 76 ( 1 ): 81 – 88 . Fischer , H. ; Schulz-Ekloff , G. ; Wöhrle , D. ( 1997 ) Oxidation of aqueous sulfide solutions by dioxygen. Part 1: Autoxidation reaction . Chemical Engineering & Technology , 20 ( 7 ): 462 – 468 . ) was calculated from the experimental data, allowing for the subsequent determination of an “apparent kinetic parameter” (k _A ), that excluding parallel reactions was between 1.7 × 10²³ – 6.2 × 10²⁴ L/(mol·h). This allowed for further tuning of the model such that the estimates of the Zn effluent concentration became of the same order of magnitude as the measured ones (10^?7 M Zn).     

ZnS微球的制备及吸光性能研究

采用溶剂热法,以醋酸锌和硫脲为原料,去离子水和无水乙醇的混合溶液为反应介质制备了ZnS微球。利用XRD、SEM、UV-Vis吸收光谱探讨了反应温度和时间对产物晶型、颗粒形貌以及吸光性能的影响。结果表明:ZnS微球的晶型和形貌对反应温度比较敏感,反应时间对晶体的结晶度和吸光率影响较大。采用溶剂热法的最佳合成温度为150℃左右,反应时间为12 h;该条件下生成的ZnS微球物相较为纯净、结晶完全,且分散性良好,带隙约为3.3 eV。     

One-step fabrication of biocompatible chitosan-coated ZnS and ZnS:Mn2+ quantum dots via a γ-radiation route

Biocompatible chitosan-coated ZnS quantum dots [CS-ZnS QDs] and chitosan-coated ZnS:Mn2+ quantum dots [CS-ZnS:Mn2+ QDs] were successfully fabricated via a convenient one-step γ-radiation route. The as-obtained QDs were around 5 nm in diameter with excellent water-solubility. These QDs emitting strong visible blue or orange light under UV excitation were successfully used as labels for PANC-1 cells. The cell experiments revealed that CS-ZnS and CS-ZnS:Mn2+ QDs showed low cytotoxicity and good biocompatibility, which offered possibilities for further biomedical applications. Moreover, this convenient synthesis strategy could be extended to fabricate other nanoparticles coated with chitosan.PACS: 81.07.Ta; 78.67.Hc; 82.35.Np; 87.85.Rs.     

花簇状ZnS:Mn微球的制备及荧光性能研究

采用CTAB辅助溶剂热法合成出花簇状结构的ZnS:Mn微球,并研究了反应温度,时间,溶剂,CTAB用量对样品形貌的影响.结果表明在170℃时加入0.8g CTAB溶剂热反应12h,所获得样品形貌规整,尺寸较均一;此外在反应体系中加入油酸获得尺寸更小的花簇状ZnS:Mn.并对花簇状结构的生长机制进行了阐述.     

CdSe/ZnS量子点掺杂聚合物光纤放大器增益特性分析

提出了一种半导体量子点CdSe/ZnS掺杂聚合物光纤放大器。测量了CdSe/ZnS量子点吸收和发射光谱,采用二能级结构和速率方程的方法,全面描述了CdSe/ZnS量子点掺杂聚合物光纤放大器的增益性能。计算了放大器增益随量子点掺杂光纤长度、量子点掺杂浓度和信号光强度的变化,给出了不同泵浦光强条件下的增益谱线及半高全宽。结果表明,在mW量级的泵浦条件下,CdSe/ZnS量子点掺杂聚合物光纤放大器可获得35dB以上的增益,获得相同增益所需泵浦光强度只有同类型染料掺杂聚合物光纤放大器的万分之一。泵浦光强与量子点掺杂浓度之间存在最佳对应关系,单位泵浦功率激发的最佳量子点数为6.33×107/mW。在室温下,CdSe/ZnS量子点掺杂聚合物光纤放大器具有550nm～610nm的带宽,含盖了聚合物光纤的低损窗口。     

Improvement of the cell performance in the ZnS/Cu(In,Ga)Se2 solar cells by the sputter deposition of a bilayer ZnO : Al film

ZnS is a candidate to replace CdS as the buffer layer in Cu(In,Ga)Se₂ (CIGS) solar cells for Cd‐free commercial product. However, the resistance of ZnS is too large, and the photoconductivity is too small. Therefore, the thickness of the ZnS should be as thin as possible. However, a CIGS solar cell with a very thin ZnS buffer layer is vulnerable to the sputtering power of the ZnO : Al window layer deposition because of plasma damage. To improve the efficiency of CIGS solar cells with a chemical‐bath‐deposited ZnS buffer layer, the effect of the plasma damage by the sputter deposition of the ZnO : Al window layer should be understood. We have found that the efficiency of a CIGS solar cell consistently decreases with an increase in the sputtering power for the ZnO : Al window layer deposition onto the ZnS buffer layer because of plasma damage. To protect the ZnS/CIGS interface, a bilayer ZnO : Al film was developed. It consists of a 50‐nm‐thick ZnO : Al plasma protection layer deposited at a sputtering power of 50 W and a 100‐nm‐thick ZnO : Al conducting layer deposited at a sputtering power of 200 W. The introduction of a 50‐nm‐thick ZnO : Al layer deposited at 50 W prevented plasma damage by sputtering, resulting in a high open‐circuit voltage, a large fill factor, and shunt resistance. The ZnS/CIGS solar cell with the bilayer ZnO : Al film yielded a cell efficiency of 14.68%. Therefore, the application of bilayer ZnO : Al film to the window layer is suitable for CIGS solar cells with a ZnS buffer layer. Copyright © 2012 John Wiley & Sons, Ltd.     

沉淀法制备ZnS∶Cr纳米晶及其光学性能研究

以十二烷基苯磺酸钠和六偏磷酸钠作为分散剂,采用沉淀法制备了ZnS及不同掺杂浓度的ZnS∶Cr纳米晶。利用XRD和TEM对纳米晶物相和形貌进行了分析。结果表明,ZnS和ZnS∶Cr纳米晶均为立方闪锌矿结构,利用谢乐公式估算ZnS和ZnS∶Cr纳米晶平均粒径分别为2.1和2.2nm。TEM观察到纳米晶近似为球形,平均粒度为3nm左右,具有较好的单分散性且分布均匀。荧光光谱(PL)表明,纳米晶在420、440和495nm处有发射谱带,前两者被认为是S空位深陷阱发光,后者被认为是表面态或中心辐射复合发光。     

溶剂热条件下制备ZnS纳米晶及其光学性质

以醋酸锌和硫脲为原料,采用溶剂热法分别以有机小分子的一元胺(甲胺、乙胺、正丁胺)和多元胺(乙胺、二乙胺、三乙胺)为介质合成ZnS纳米粉体,通过XRD和SEM对所得ZnS粉体进行了表征,研究了不同介质对所得ZnS粉体的晶相组成、颗粒尺寸及形貌的影响.结果表明,在单胺体系中,随着碳链的增长,ZnS粉体六方相的生长趋势渐弱;在伯仲叔胺中,随着与氨基相连的碳原子上氢原子的减少,六方相的生长趋势渐弱,在三乙胺中甚至出现了立方ZnS的特征峰.荧光光谱的研究表明,从伯胺到叔胺,其发射峰发生少量的红移,从乙胺溶液中的450nm附近红移到三乙胺溶液中的500nm附近.     

ZnS-based visible-blind UV detectors: Effects of isoelectronic traps

The aim of this study is to reveal the underlying cause of the gradual turn-on characteristic of low Te containing ZnSTe Schottky barrier photodiodes. The results of photoresponse studies on ZnS, ZnSSe and ZnSTe diodes indicate that the Te isoelectronic trapping effect is responsible for the gradual turn-on characteristic of low Te containing ZnSTe Schottky barrier photodiodes. The results also reveal that the ZnSSe diode, having the advantage of being free of isoelectronic centers, is a more suitable choice for applications requiring high visible rejection power. It is demonstrated that highly UV sensitive responsivity with an abrupt long wavelength cutoff tailored to lie between 340–400 nm can be achieved in the ZnSSe diode system.