~ ~ 3＋ Sol-gel synthesis and photoluminescence characterization of La2Ti2O7.EU3＋nanocrystals

Eu³⁺ doped La₂Ti₂O₇ nanocrystals with pure monoclinic phase and size of about 100 nm were prepared by a citric acid (CA) assisted sol-gel method. Techniques of thermo-gravimetric (TG) and differential scanning calorimetry (DSC), X-ray diffraction (XRD), as well as transmission electron microscopy (TEM) were employed to characterize the as-synthesized nanoparticles. Furthermore, photoluminescence (PL) performances of the Eu³⁺ doped La₂Ti₂O₇ nanocrystals were evaluated with focus on the effects of calcination temperature and Eu³⁺ doping concentration on the photoluminescence properties.     

2-（4-咪唑基苯乙烯基）-8-羟基喹啉锌的合成与光致发光特性

合成了一种新型的2-（4-咪唑基苯乙烯基）-8-羟基喹啉配体以及其金属锌配合物,用红外光谱（IR）、紫外光谱（UV）、元素分析（EA）、核磁共振氢谱（1H NMR）等确认了化合物的结构,通过荧光光谱测定了配合物的荧光性质,证实其具有良好的光致发光性能,最大发射波长为576 nm;热重分析实验也表明了金属锌配合物有很好的热稳定性。     

超声喷雾热分解法制备p型氧化锌多晶薄膜

采用超声喷雾热分解法在玻璃衬底上以醋酸锌水溶液[Zn(CH3COO)2·2H2O]、醋酸铵(CH3COONH4)和硝酸铝[Al(NO3)3·9H2O]的混合溶液为前驱体生成了N-Al共掺P型氧化锌薄膜.考察了前驱体溶液浓度、载气流速、热解温度对实验结果的影响.用XRD和SEM测试手段对薄膜进行了晶体结构和表面形貌的表征,结果表明所制备的薄膜为六角纤锌矿结构的氧化锌薄膜,表面均匀,结构致密,具有强烈的呈c轴垂直于衬底的(002)择优取向.对薄膜进行了电学测试和光致发光性能测试,结果表明制备的薄膜为P型氧化锌薄膜,薄膜的光致发光明显具有氧化锌薄膜的特点.     

氧化锡纳米线的光致发光性能分析

通过热蒸发沉积法在常压、900°C高温条件下,合成了氧化锡纳米线结构。利用扫描电子显微镜、透射电子显微镜及选区电子衍射对样品的表面形貌和微结构进行了表征,X射线衍射、傅里叶变换红外光谱进一步证明所制纳米结构为金红石型氧化锡单晶结构。在77K和300K温度条件下,研究了所制氧化锡纳米线及其在氧气气氛中退火后的光致发光性能。     

阱宽对GaAs/Al0.3Ga0.7As量子阱红外探测器光谱响应的影响

采用金属有机物化学气相沉积法(MOCVD)生长 了两种不同结构参数的GaAs/Al0.3Ga0.7As红外量子阱材料, 利用傅里叶光谱仪,分别对阱宽为4.5与5.0nm的样品进行77K液氮 温 度下光谱响应测试及室温光致发光(PL)光谱 测试,样品的峰值响应波长分别为8.39、7.69μm,与根据薛定谔方 程计算得到 的峰值波长8.92、8.05μm的误差分别为6.36%、4.70%。对吸收峰向高能方向发生漂移的现象进行了分析讨论,认为势阱变窄时阱中的 应 力作用较强是导致峰值波长红移的原因,而与GaAs阱中进行适度Si掺杂无关。PL实验结果与 理论计算相符合,表明增加阱宽是量子阱带间跃迁能量升高的原因。据此可实现对量子阱能 级的微调,从而满足对不同波长探测的需要。     

Ag掺杂浓度对ZnO纳米花荧光增强的影响

采用水浴与光照相结合的方法制备了Ag/ZnO纳米复 合结构,研究了不同Ag掺杂浓度对 ZnO发光强度的影响。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光 (PL)光谱对Ag/ZnO纳米复合物的结构、形貌和光学性能进行了研究。SEM表明,由水浴法制 得的ZnO纳米花结构长约1.0μm,直径为200nm左右。XRD结果显示,Ag掺杂后Ag/ZnO 纳米复合结构衍射峰的强度都增强,当掺杂浓度为0.153wt%时,在38.28°出现了Ag₂O的衍射峰。PL表明,Ag浓度极大影响了ZnO紫外发光强度。当Ag的掺杂 浓度为0.051wt% 时,Ag/ZnO纳米复合结构具有最强的紫外发射强度,同未掺杂的ZnO相比,紫外发光强度提 高了11倍。研究结果表明,利用Ag纳米颗粒的局域表面等离子共振(LSPR)特性增强了ZnO纳 米结构的荧光强度,从而提高了荧光检测的灵敏度。     

Influence of the chromium and ytterbium co-doping on the photoluminescence of zinc selenide crystals

The luminescent properties of ZnSe, ZnSe：Cr（0.05 at.% Cr）, ZnSe：Yb（0.03 at.% Yb） and ZnSe：Cr：Yb（0.05 at.% Cr, 0.05 at.% Yb） crystals, doped during the growth process by the chemical vapor transport method, were studied within the temperature interval of 6–300 K. At the 6 K temperature in the visible spectral range 2 bands were observed： a band in the excitonic spectral region and a band of self-activated luminescence. It was shown that co-doping of zinc selenide crystals with the chromium and ytterbium led to the combination of the impurities influence on the photoluminescent properties. At the liquid helium temperature in the middle infrared range of the spectra of the ytterbium and chromium co-doped crystal a band with the maximum localized at 1.7μm was observed, which was overlapped with a complex band in the middle-IR spectral range, characteristic for the chromium doped ZnSe crystals. On the basis of obtained data an interaction mechanism of the chromium and ytterbium co-doping impurities was proposed. Guided by the existent model of the ytterbium ion incorporation in the selenide sublattice of the ZnSe crystals, an assumption about stabilization of single charged chromium ions in the zinc sublattice crystal nodes, by means of formation of the local charge compensating clusters, was made. It was assumed that the resonant energy transfer from one chromium ion to another,which led to the concentration quenching of the IR emission in the ZnSe：Cr PL spectra, would lead to the broadening of the IR emission in the spectra of ytterbium and chromium co-doped zinc selenide crystals.g     

弱酸环境下硅纳米线的水热可控合成及其光学性能

以去离子水为溶剂,SiO为硅源,调节溶液的pH为6,加热至470℃,8 MPa保温8 h,成功制备出硅纳米线。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射显微镜(TEM)对硅纳米线进行了结构和形貌表征,采用光致发光(PL)光谱分析了硅纳米线的光学性能。结果表明:硅纳米线为立方金刚石结构,其生长端呈半圆形的闭合结构,纳米线由晶面间距约0.31nm的晶体硅内核与厚度小于10 nm的无定形氧化硅外鞘两部分组成;PL光谱显示硅纳米线在431 nm和462 nm处具有良好的发光性能。     

射频磁控溅射制备高In组分Al1-xInxN薄膜及其光学性能

采用射频磁控溅射法,在硅和石英衬底上生长了高In组分Al_(1-x)In_xN薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外-可见-红外分光光度计分别对Al_(1-x)In_xN薄膜的结构、形貌和光学带隙进行表征,并在室温下测量Al_(1-x)In_xN薄膜的光致发光(PL)谱。结果表明:Al_(1-x)In_xN薄膜均呈(002)择优取向,具有单相纤锌矿结构,In组分为x=0.64-0.76。随着In组分升高,薄膜表面更加光滑,光学带隙值由1.93 eV红移至1.87 eV。In组分x=0.64,薄膜以本征发光为主,随着In组分增加,出现了附加的发光峰,这可归因于Moss-Burstein效应。     

研究速递

赫尔辛基大学研发出多点触控大型显示屏显微镜芬兰赫尔辛基大学联合MultiTouch公司研究人员共同研发出新型多点触控显示屏显微镜。这项新技术将显微镜和一个46英寸多点触控显示屏通过网络连接,显微镜扫描样本后,可生成一个由多达5万张独立图像拼接