核壳结构型ZnS包覆ZnS：Cu的合成及其发光性能研究

利用液相化学方法并添加有机表面活性剂合成了ZnS：Cu／ZnS核壳结构,X射线衍射表明,所合成的ZnS具有闪锌矿结构,随着ZnS包覆量的增加,核壳结构尺寸增大并在紫外-可见光谱图中的吸收峰出现红移,荧光光谱中,该纳米材料在510nm处出现荧光发射峰,主要是由于Cu2＋在t2能级上的复合跃迁。作为表面钝化层,ZnS的包覆有效地降低了晶体中Cu2＋的无辐射复合,并明显改善了znS：Cu的发光强度和发光寿命。     

ZnS：Mn^2＋,Eu^3＋发光纳米材料的油-水界面法合成

以硬脂酸锌为Zn源、硫化钠为S源,首次采用油水界面法制备出单分散于环己烷和甲苯的ZnS纳米材料,探索有机溶剂、锌源和油酸浓度等对紫外吸收影响的同时,以ZnS为基质,掺杂Mn^2＋和Eu^3＋制得ZnS：Mn^2＋,Eu^3＋发光纳米材料,采用高分辨率透射电子显微镜（HRTEM）、X射线粉末衍射仪（XRD）、紫外可见（UV-VIS）和荧光分光光度计（PL）对产物进行了表征,紫外和HRTEM测试结果均表明,产物为单分散性,平均粒径为4.3 nn;荧光测试表明,产物所发荧光较强,肉眼可观测到明显的橙黄色（585 nm）和橙红色（616 nm）发光;XRD结果显示,产物结构为立方闪锌矿结构     

Mn,Cu掺杂对ZnS∶Mn,Cu电致发光材料亮度的影响

采用水热法制备了ZnS∶Mn,Cu电致发光材料,利用透射电镜对发光材料的结构和形貌进行表征,并且探讨了Cu2+、Mn2+掺杂量和反应温度对ZnS∶Mn,Cu发光材料亮度的影响。结果显示,随着Cu2+、Mn2+掺杂量的增加,发光材料的亮度也随之增加,但对于Cu2+、Mn2+掺杂都存在最佳值,当Cu2+掺杂量0.2%,Mn2+掺杂量4%,温度150℃时,得到的电致发光材料亮度较高,粒径约10nm左右。     

Mn~(2+)掺杂水溶性ZnS量子点的制备及其光致发光性能

采用共沉淀法,在3-巯基丙酸(MPA)为表面修饰剂下,成功制备出Mn2+掺杂水溶性ZnS量子点。利用X射线衍射仪、透射电子显微镜、紫外-可见吸收光谱仪和荧光分光光度计等表征方法研究了Mn2+掺杂剂及掺杂量对ZnS量子点的晶体结构、形貌和发光性能等的影响。结果表明,所得产物为ZnS立方型闪锌矿结构,样品呈不规则球形,粒径主要集中在9.7nm左右;在320nm激发下,Mn2+掺杂ZnS量子点出现两个发射波峰,分别位于587和637nm处,其中587nm处的发射波峰为ZnS表面态缺陷发光,而637nm处的发射波峰则属于Mn2+∶4T1-6A1能级特征发光。同时,利用红外吸收光谱对Mn2+掺杂水溶性ZnS量子点的形成机理进行了初步探讨。     

化学合成法制备ZnS基纳米荧光粉研究

描述了一种生产ZnS:M[M=Mn,Cu,Cu(Al)]纳米荧光粉的化学合成方法.运用本方法通过调节巯基乙酸与甲基丙烯酸的摩尔比,可在1.8～3.0nm范围内控制纳米粒子的尺寸.选择面积的电子衍射和X射线衍射证明ZnS:M纳米荧光粉具有闪锌矿结构.透射电镜图像表明ZnS:M纳米荧光粉具有较好的尺寸分布.ZnS:Mn的PL谱表明纳米尺寸的ZnS:Mn与体材料相比具有较高的发光效率。     

掺杂硫化锌的制备与光学特性的研究

采用共沉淀法制备Co~(2+)/Ni~(2+)掺杂的ZnS纳米材料,对所制备样品进行XRD、SEM和PL表征。结果表明,样品的发光峰是ZnS及掺杂离子复合作用产生的发光峰,样品分别在438nm、469nm、504nm、531nm、562nm和602nm波段表现出发光特性,并简要介绍其发光机理。     

核壳结构CdS：Mn/ZnS纳米晶的制备与光学性能研究

以3-巯基丙酸为稳定剂,采用共沉淀法在水相中合成了CdS∶Mn掺杂纳米晶,然后进一步将ZnS包覆于CdS∶Mn纳米晶表面,制备了CdS∶Mn/ZnS核壳结构纳米晶。利用X射线衍射（XRD）,透射电子显微镜（TEM）和紫外-可见吸收光谱（UV-Vis）对纳米晶的结构、形貌和光学性质进行了表征,发现制备的纳米晶具有优秀的单分散性,确认合成了CdS∶Mn/ZnS核壳结构纳米晶。通过荧光光谱（PL）研究了纳米晶的发光性质和光稳定性,结果表明包覆壳层后纳米晶的发光强度显著提高,最高可达8倍,且Mn2＋离子的发光峰峰位置随着ZnS壳层数的增加而红移。此外,核壳纳米晶的光稳定性大大提高。     

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。     

Mn或Cu掺杂非晶AlN薄膜的光致发光特性

研究了Mn或Cu掺杂的非晶AlN薄膜在室温下的发光性质。Cu或Mn掺杂的非晶AlN薄膜是在玻璃衬底上采用中频反应磁控溅射制备的。X射线衍射（XRO）结果表明薄膜为非晶。由X射线能谱（EDX）检测分析结果得到薄膜中Cu和Al含量比例为1：10，Mn和Al含量比例为1：15。光致发光光谱表明Cu掺杂的AlN薄膜能发出强烈的蓝光（～430m）而Mn掺杂则表现为红光（～650nm）。     

ZnS:Mn荧光粉的溶剂热法制备及其发光性能

采用溶剂热法合成了ZnS∶Mn荧光粉,讨论了锰掺杂量对硫化锌发光性能的影响。通过扫描电镜(SEM)、X射线粉末衍射仪(XRD)、紫外可见分光光度计(UV-Vis)和荧光分光光度计(PL)对合成的ZnS∶Mn荧光粉的结构和光学性能进行了表征。结果表明:ZnS∶Mn荧光粉的平均粒径为13.5nm,在波长340nm~200nm处有强吸收,Mn离子浓度在所研究范围内,锰掺杂量对硫化锌的晶型、结晶度、粒径无影响,但对其能级结构影响显著,且随着Mn离子掺杂量的增加,发光强度先增加后减小,掺杂量为5%时达到最大值。     

Photoluminescence enhancement of synthesized ZnS-based-nanocrystals and aging effect on its emitting color

Various colors-emitting ZnS:Cu,Cl, ZnS:Cu,Cl,Mn and ZnS:Mn nanocrystals (NCs) which were shown to be about 3 nm sized-particle were synthesized by using a solution chemistry. And the luminescences of the synthesized ZnS-based NCs were investigated through photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopy. The PLE and PL intensities of the ZnS-based NCs depends on their reflux time, and red shifted maximum PLE wavelengths of the synthesized NCs showed with increasing reflux time. The increased maximum PL intensity of NCs with increasing reflux time is due to the enhanced crystallinity of the NCs. And the shifted emitting colors of the NCs showed after aging treatment compared to those of refluxed NCs. The amount of shifted wavelength of Cu,CI doped ZnS, Cu,CI and Mn co-doped ZnS, only Mn doped ZnS NCs were -22 nm, +18 nm, and +14 nm, respectively.     

Effect of zinc oxide concentration in fluorescent ZnS:Mn/ZnO core–shell nanostructures

In the present work, we have prepared zinc sulphide (ZnS:Mn)/zinc oxide (ZnO) core–shell nanostructures by a chemical precipitation method and observed the effect of ZnO concentration on the fluorescent nanoparticles. Change in the morphological and optical properties of core–shell nanoparticles have been observed by changing the concentration of ZnO in a core–shell combination with optimum value of Mn to be 1 % in ZnS. The morphological studies have been carried out using X-ray diffraction (XRD) and transmission electron microscopy. It was found that diameter of ZnS:Mn nanoparticles was around 4–7 nm, each containing primary crystallites of size 2.4 nm which was estimated from the XRD patterns. The particle size increases with the increase in ZnO concentration leading to the well-known ZnO wurtzite phase which was coated on the FCC phase of ZnS:Mn. Band gap studies were performed by UV–visible spectroscopy and a red shift in absorption spectra have been observed with the addition of Mn as well as with the capping of ZnO on ZnS:Mn. The formation of core–shell nanostructures have been also confirmed by FTIR analysis. Photoluminescence studies show that emission wavelength is red shifted with the addition of ZnO layer on ZnS:Mn(1 %). These core–shell ZnS:Mn/ZnO nano-composites will be a very suitable material for specific kind of tunable optoelectronic devices.     

Synthesis and optoelectrochemical properties of ZnS:Mn nanocrystals

Mn2+ ions doped ZnS semiconductor nanocrystals (ZnS:Mn NCs) were synthesized using colloidal chemical method at 70 degrees C without any capping agents. The as-prepared undoped ZnS and ZnS:Mn NCs were characterized by UV-Vis absorption spectra, fluorescent emission spectra, X-ray powder diffraction (XRD), inductively coupled plasma analysis (ICP), X-ray photoelectron spectroscopy (XPS), Dynamic light scattering (DLS), cyclic voltammogram and electronic transmission microscopy (TEM). The dependence of photoluminescence of ZnS:Mn NCs on dopant concentration was studied. The results show that Mn2+ ions mainly stay at ZnS nanocystal surface, and Mn2+-surface defect state complex was formed, as a result of which, surface defect emission of ZnS nanocrystals was substituted with Mn2+-related PL emission. The strongest fluorescent emission intensity was obtain at 1.85 at% Mn2+ doped ZnS:Mn NCs. The Mn2+ doped ZnS:Mn NCs are of 5 nm in diameter. The emission peak at 575 nm is attributed to d-d (4T1 --> 6A1) transition of Mn2+ ions. The existence of Mn2+-related photoluminescence could be well correlated with cyclic voltammogram of Mn2+-doped NCs, where pair of oxidation and reduction peaks were clearly observed due to the doped Mn2+ ions. The adsorbed Mn2+ ions on ZnS NCs produced neither Mn2+ emission nor redox peaks. For heavily doped ZnS:Mn NCs (4.87 at%), redox peaks gap in cyclic voltammogram became larger and new oxidation peak appeared. Correspondingly, when the Mn2+ doping concentration reached 4.87 at%, the Mn2+-related emission totally disappears due to the Mn-Mn interactions. This work implys that electrochemical technique is possibly an useful tool to probe the local structure of doped Mn2+ ions.     

Triboluminescent properties of zinc sulfide phosphors due to hypervelocity impact

The emission of light due to crystal fracture, or triboluminescence (TL), is a phenomenon that has been known for centuries. One of the most common examples of TL is the flash created from chewing Wint-O-Green Lifesavers^®. From 2004 to 2006, research was completed using the two-stage light gas gun located at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama to measure the TL properties for zinc sulfide doped with both manganese (ZnS:Mn) and copper (ZnS:Cu). Results clearly show that hypervelocity impact-induced TL has been observed for both ZnS:Mn and ZnS:Cu. For ZnS:Mn, TL produced during 4.7 and 5.7 km/s impacts was statistically more luminous than was observed from similar data collected at 3.3 km/s. The TL decay time for ZnS:Mn was found to be 292 ± 58 μs, which is totally consistent with earlier measurements that did not use impact as an excitation source. Further, the emission of TL from ZnS:Mn undergoing hypervelocity impact has been demonstrated to have a significant component at the known peak emission wavelength of ZnS:Mn of 585 nm. Small TL emission generated as a result of hypervelocity impact was also observed from ZnS:Cu. The most intriguing conclusion from this research is that it may be possible to discriminate impact velocity by measuring the time-integrated luminosity of TL phosphors. An ability to measure the velocity of a hypervelocity impact is a significant indicator of the potential usefulness for this concept for use as an impact sensor in future spacecraft.     

A facile and fast approach for the synthesis of doped nanoparticles using a microfluidic device

The microfluidic approach emerges as a new and promising technology for the synthesis of nanomaterials. A microreactor allows a variety of reaction conditions to be quickly scanned without consuming large amounts of raw material. In this study, we investigated the synthesis of water soluble 1-thioglycerol-capped Mn-doped ZnS nanocrystalline semiconductor nanoparticles (TG-capped ZnS:Mn) via a microfluidic approach. This is the first report for the successful doping of Mn in a ZnS semiconductor at room temperature as well as at 80?°C using a microreactor. Transmission electron microscopy and x-ray diffraction analysis show that the average particle size of Mn-doped ZnS nanoparticles is ～3.0?nm with a zinc-blende structure. Photoluminescence, x-ray photoelectron spectroscopy, atomic absorption spectroscopy and electron paramagnetic resonance studies were carried out to confirm that the Mn(2+) dopants are present in the ZnS nanoparticles.     

Multicolor luminescence from transition metal ion (Mn2+ and Cu2+) doped ZnS nanoparticles

Mn and Cu doped ZnS nanoparticles in powder form were prepared by a simple solvothermal route. Particle size and crystal structure of the products were investigated through X-ray diffraction study revealing the formation of cubic ZnS nanoparticles of average diameter 2.5 nm. Particle size was also verified by the high resolution transmission electron microscopic images. Blue emission at approximately 445 nm was observed from the undoped sample, which was attributed to the presence of large surface defects. With increasing doping concentration the defect related emission gradually quenches and subsequently the impurity related emissions appeared. Mn doped samples exhibited orange emission at approximately 580 nm which may be attributed to the transition between (4)T1 and (6)A1 energy levels of the Mn2+ 3d states. Whereas, the Cu doped ZnS nanoparticles exhibited a red shifted strong blue emission at approximately 466 nm which is attributed to the transition of the electrons from the surface states to the 't2' levels of Cu impurities.