掺铝二氧化锡气敏材料的制备与性能研究

用sol-gel法制备了8种掺铝SnO2气敏材料,并用XRD分析其结构和晶粒度,用自组装仪器测定其气敏性能。结果表明:铝的掺入未改变SnO2的四方晶系结构,样品晶粒度为31.46～50.89nm;烧结温度600℃、掺铝量为5%(摩尔分数)的样品对C4H10的灵敏度为22.7;烧结温度600℃、掺x(Al)为1%的样品对H2S比较敏感,灵敏度为87.5;烧结温度700℃、掺x(Al)为5%的样品对C4H10灵敏度为45.5,对H2S灵敏度为100。     

非晶SiO2纳米线的合成及其显微结构和光学性质的研究

本研究以硅片为衬底,热蒸发一氧化硅粉末在较低温度下合成了大量直径均匀的非晶SiO2纳米线.这些纳米线直径分布在15 nm～40 nm之间,长度几十微米.选区电子衍射(SAED)、能谱(EDS)、电子能量损失谱(EELS)分析结果表明这些纳米线为非晶SiO2纳米线.光致发光(PL)谱测试结果显示纳米线在波长550 nm处存在一个较强的PL峰.本文进一步指出了蒸发源SiO粉末的颗粒度和蒸发温度对纳米线生长有强烈的影响.     

磁控反应溅射SnO2薄膜的气敏特性研究

为研究SnO2薄膜的气敏特性,采用直流磁控反应溅射法制备了SnO2薄膜。探讨和分析了SnO2薄膜气敏元件的敏感机理。对SnO2薄膜的电阻和灵敏度的测试以及对实验结果的分析表明:SnO2薄膜厚度在150~400nm为宜,一般膜厚在250nm时较为敏感。在SnO2薄膜中掺入Pd、Pt、Ag等微量杂质可大大提高SnO2薄膜气敏元件的灵敏度,且使灵敏度的峰值向低温方向移动,增强了对H2、CO和C2H5OH等可燃气体的选择性、响应时间由3min缩短到0.5s以下。     

退火处理对二氧化锡纳米线性能的影响

采用化学气相沉积法在硅衬底上生长二氧化锡(SnO2)纳米线,并对其进行热处理.扫描电子显微镜、X射线衍射仪和拉曼光谱测试分析表明所合成的SnO2蚋米线为单一四方金红石相,且结晶性能良好.光致发光测试显示在576 nm附近有明显的黄色发光峰,但在氧气氛环境退火处理后该发光峰逐渐减弱,表明576 nm处的发光峰为氧空位缺陷引起的发光.同时,退火处理能有效提高材料的场发射性能,SnO2纳米线的最低开启和阚值电场分别约为4.6和6.2 V/μm.     

氮化法合成掺钇氮化铝纳米线

采用直流电弧等离子体辅助法,使钇铝合金(Al:Y)和氮气直接反应,成功合成了掺钇氮化铝(AlN:Y)纳米线。用XRD、SEM和拉曼光谱对所制样品的结构和形貌进行了表征,利用PL光谱和磁滞回线研究了AlN:Y纳米线的光学性质和磁性。AlN:Y纳米线长度约为10μm,直径在40～50 nm。纳米线的发光中心位于533 nm,展现出了良好的室温铁磁性。     

美国研制出白光ZnO纳米线LED

美国波特兰大学研制出发射白光的ZnO纳米线发光 二极管(LED)。该大学研究人员在透明聚合物中埋置垂直 定向的ZnO纳米线获得了白光LED。 研究人员在水溶液中采用低温电子淀积技术,在掺氟 的SnO2涂层玻璃上制作了LED。在5 cm×5 cm衬底上     

Ag纳米线掺杂的液晶显示器件的电-光特性

为了降低液晶显示器(LCD)的能耗,制备了Ag纳米线-液晶复合材料。用不同浓度的直径约为50nm的Ag纳米线掺杂在液晶中,制备了扭曲向列相液晶显示(TN)模式液晶盒,研究了Ag纳米线对TN显示模式液晶盒的驱动电压、开态响应时间以及频率调制特性的影响。液晶电-光性能的研究结果表明,Ag纳米线的加入能显著降低TN显示模式液晶盒的驱动电压,最大降幅可达14%;但液晶盒的响应时间在掺杂Ag纳米线掺杂后有一定程度的增加。此外,Ag纳米线掺杂的液晶显示出很强的频率调制特性。Ag纳米线的掺杂可以有效改善TN显示模式液晶的电-光性能。     

Ag纳米颗粒对Er~(3+)/Tm~(3+)/Yb~(3+)共掺铋锗酸盐玻璃上转换发光特性的影响

采用传统熔融淬冷法制备了系列Er3+/Tm3+/Yb3+共掺复合Ag纳米颗粒的铋锗酸盐玻璃样品。从吸收光谱中确定了Ag纳米颗粒表面等离子体共振(SPR)峰位于545nm附近;透射电镜(TEM)图像中观察到均匀分布的Ag纳米颗粒,尺寸约为6~18nm。研究了纳米Ag含量对Er3+/Tm3+共掺复合Ag纳米颗粒铋锗酸盐玻璃上转换发光特性的影响,结果表明,Tm3+离子472nm处的上转换蓝光、Er3+离子525nm处的上转换绿光、543nm处的上转换绿光和661nm处的上转换红光发光强度在AgCl含量的质量百分数为1%时达到最大值,与未掺杂AgCl的基质玻璃相比,分别提高了约3.2、3.8、5.4和2.3倍。     

ZnO：Ag薄膜的结构对其紫外发光增强的研究

利用脉冲激光沉积方法(PLD),在Si(100)衬底上生长了银掺杂的氧化锌薄膜(ZnO:Ag),所用的激光波长分别是1064 nm和355 nm.通过x射线衍射分析发现,两种不同激光沉积样品的晶体结构有很大的区别.此外,由1064 nm激光制备的ZnO:Ag薄膜,在氧气中800℃的条件下退火一个小时后,在其光致发光(PL)谱中发现,样品的紫外发光峰强度随薄膜中Ag含量增加而急剧增强,但在同样条件下处理的由355 nm激光制备的薄膜,没有观察到类似现象.经过分析和比较,我们认为这种紫外发光增强的特殊现象,是ZnO:Ag薄膜中的纳米Ag颗粒所引起的局部等离子共振而导致.     

Ag纳米线的一步法合成和导电性能原位测量

以硝酸银、乙二醇和聚乙烯吡咯烷酮为原料,采用一步法化学合成Ag纳米线。研究了合成温度对产物的影响,发现合成温度为160℃时能得到直径约60 nm的均匀的Ag纳米线,温度过高或过低都仅能得到Ag纳米颗粒。采用原位测试系统测量了单根Ag纳米线的导电性能,测得其电导率约1.5!105S/cm。     

Silver nanoparticles and silver molybdate nanowires complex for surface-enhanced Raman scattering substrate

Selective synthesis of silver and uniform single crystalline silver molybdate nanowires in large scale can be easily realized by a facile soft template approach.Ag6Mo10O33 nanowires with a uniform diameter of about 50nm and the length up to several hundred micrometers were synthesized in large scale for the first time at room temperature using 12-silicotungstic acid system. The silver nanoparticles can be easily synthesized with the assistance of UV-light. Sensitive surfaceenhanced Raman scattering signals of p-aminothiophenol were observed on Ag nanoparticles and silver molybdate nanowires complex. The results demonstrated that synthetic method could be a potential mild way to selectively synthesize various molybdate nanowires with various phases in large scale. The silver nanoparticles and silver molybdate nanowires complex would be proposed for surface-enhanced Raman scattering substrate.     

An MWCNT-doped SnO_2 thin film NO_2 gas sensor by RF reactive magnetron sputtering

An MWCNT-doped (multi-walled carbon nanotube) SnO_2 thin film NO_2 gas sensor, prepared by radio frequency reactive magnetron sputtering, showed a high sensitivity to ultra-low concentrations of NO_2 in the parts per billion range. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM) characterizations indicated that the MWCNTs were affected by the morphology of the SnO_2 thin film and the particle size.The properties of the MWCNT-doped SnO_2 sensor, such as sensitivity, selectivity, and response-recovery time, were investigated. Experimental results revealed that the MWCNT-doped SnO_2 thin film sensor response to NO_2 gas depended on the operating temperature, NO_2 gas concentration, thermal treatment conditions, film thickness, and so on.The mechanism of the gas-sensing property of the MWCNT-doped SnO_2 thin film sensor was investigated and showed that the improved gas-sensing performance should be attributed to the effects between MWCNTs (p-type) and SnO_2 (n-type) semiconductors.     

能量转换效率达10.2%的非晶硅单结太阳能电池

本文报道我们在非晶硅单结太阳能电池方面的研究结果。电池采用的结构为Glass/SnO_2/Pin/Ag,其能量转换效率在1cm~2面积上达到10.2％(AM1.5,100mW/cm~2),在0.126cm~2面积上达到11.1％。     

Sb掺杂SnO2/SiO2纳米光学气敏薄膜的制备及其性质

采用溶胶凝胶(sol-gel)工艺制备了Sb掺杂SnO2/SiO2复合膜。通过X射线衍射(XRD)、傅立叶变换红外谱(FT-IR)及原子力显微镜(AFM)表征了薄膜样品的物相结构与表面形貌,利用紫外-可见光谱研究了复合薄膜光学特性．利用p-偏振光双面反射法对薄膜的气敏特性进行了测试。实验结果表明,薄膜中的晶粒具有纳米尺寸(～35nm)的大小．比表面积大,孔隙率高;薄膜的透光率高,可见光波段近95％;纳米Sb：SnO2：SiO2复合膜的气敏灵敏度高于纯SnO2薄膜及Sb掺杂的SnO2薄膜。     

Selective Patterned Growth of Single‐Crystal Ag–TCNQ Nanowires for Devices by Vapor–Solid Chemical Reaction

We report the deterministic growth of individual single‐crystal organic semiconductor nanowires of silver–tetracyanoquinodimethane (Ag–TCNQ) with high yield (>90%) by a vapor–solid chemical reaction process. Ag–metal films or patterned dots deposited onto substrates serve as chemical reaction centers and are completely consumed during the growth of the individual or multiple nanowires. Selective‐area electron diffraction (SAED) revealed that the Ag–TCNQ nanowires grow preferentially along the strong π–π stacking direction of Ag–TCNQ molecules. The vapor–solid chemical reaction process described here permits the growth of organic nanowires at lower temperatures than chemical vapor deposition (CVD) of inorganic nanowires. The single‐crystal Ag–TCNQ nanowires are shown to act as memory switches with high on/off ratios, making them potentially useful in optical storage, ultrahigh‐density nanoscale memory, and logic devices.     

银纳米线在Si(5512)表面上自组装(英文)

由于银不会在硅表面与硅形成任何硅化物,银线成为在具有排状结构的Si(5512)表面自组装纳米线的候选材料。本研究试用不同的银覆盖度和退火温度制作高纵横比的银纳米线。当覆盖度为0.1单原子层,先后两次退火温度分别为500℃和600～700℃,经缓慢冷却过程,非常规则的银链优先吸附在Si(5512)面的四聚体上,从而形成高纵横比的银纳米线。这一自组装的两步退火过程可理解为:低温退火使吸附的银原子与Si表面结合;高温退火提供银原子扩散到Si表面四聚体位置的能量。     

Inkjet-printed Ag grid combined with Ag nanowires to form a transparent hybrid electrode for organic electronics

Networks of silver nanowires (AgNW) have been shown to facilitate high transparency, high conductivity, and good mechanical stability. However,the loose characteristic and local insulation problems due to gaps between the nanowires limit their application as electrodes. This study investigates an inkjet-printed Ag grid combined with AgNW to form a transparent hybrid electrode. The printed Ag grid on AgNW film connects the gaps between the Ag nanowires to increase the overall electric conductivity. The printed Ag-grid/AgNW hybrid electrodes have low resistivity (22.5 Ω/□) while maintaining a high transmittance (87.5%). These values are similar to standard indium tin oxide (ITO) on glass which has resistivity of 20Ω/□ and transmittance of 89% at 550 nm. In addition, these hybrid electrodes are also very flexible when fabricated on a photopolymer substrate. A spin-coating process combined with a peel-off process enable the fabrication of flexible ultra-smooth Ag-grid/AgNW electrodes. We tested the transparent and flexible electrode as the anode of a flexible organic light emitting diode (F-OLED). The light emitting layer of the F-OLED is 35 nm thick tris-(8-hydroxyquinoline) aluminum doped with 0.5% 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1)-benzopyropyrano(6,7-8-I,j)quinolizin-11-one. The maximum brightness and current efficiency of the F-OLED are 10000 cd/m² and 12 cd/A, respectively, even when bent around a radius of 2 mm. The good performance of the device with Ag-grid/AgNW hybrid electrodes show that enhanced conductive inkjet-printed Ag nanoparticles combined with Ag nanowires can produce high quality electrodes for flexible organic optoelectronic devices.     

低维纳米材料中五次孪晶结构的透射电镜研究

本文对Ag纳米线中的五次孪晶结构进行了深入系统的透射电镜研究。首次获得了Ag纳米线截面的五次孪晶结构的高分辨图像和电子衍射花样;研究了单根孪晶Ag纳米线中五次孪晶的结构特性。结果表明:Ag纳米线沿着[110]方向生长,具有显著的五次孪晶结构特点,其中五次孪晶是由五个{111}晶体旋转组成。并针对五重旋转孪晶产生7°20′本征间隙的这一典型结构问题,进行了统计实验分析,提出了纳米线中五次孪晶的新的结构模型。电子能量损失谱(EELS)研究表明:五次孪晶的中心部位相对于Ag单晶,其Ag M4,5峰向低能量方向有轻微漂移。单根纳米线的选区电子衍射或者是由[112]和[110]方向,或者是由[110]和[111]方向叠加产生的。对五次孪晶纳米线高温动态行为的透射电镜原位观察将有利于了解纳米线的生长机理。     

SnO_2-LiZnVO_4系棒状与球形晶粒湿敏陶瓷特性研究

对比研究了尿素共沉淀法和氨水共沉淀法制备出SnO_2-LiZnVO_4系湿敏陶瓷的显微结构和湿敏特性,考察了液相掺杂LiZnVO_4对材料湿敏特性的影响.实验结果表明,采用尿素共沉淀法制备出的SnO_2-LiZnVO_4系湿敏材料具有棒状晶粒的微结构,而采用氨水共沉淀法制备出的该系湿敏材料具有球形晶粒的微结构.湿敏特性表明,2种微结构的湿敏材料都是液相掺杂LiZnVO_4的摩尔分数为10%时可使材料湿敏性能最好.但棒状晶结构的SnO_2-LiZnVO_4系湿敏材料低湿电阻更小,灵敏度更适中.频率特性表明,测试频率对2种试样的阻抗-相对湿度特性曲线影响都较大.稳定性分析表明,棒状晶结构的试样比球形晶粒结构的试样更稳定.     

阳极氧化法制备氧化铝纳米线

将Al片在较高的电压下进行阳极氧化,制备了氧化铝纳米线。其形成机制主要是多孔氧化铝膜生长的同时,其微结构单元阵列在薄膜应力作用下沿薄壁处破裂,从而生成了氧化铝纳米线。扫描电镜和透射电镜观测表明,所得产物结构外形基本一致,呈凹柱面正三棱柱形,表观直径约30～300nm,长度为几微米至数十微米。采用BET法对产物的比表面积进行测量,实验值为5.8×104m2/kg,接近于理论计算值6.2×104m2/kg。实验表明,这种氧化铝一维纳米结构材料对超小Ag和CdS纳米颗粒具有较强的吸附能力,对很难用传统的过滤和离心沉淀法去除的超小纳米颗粒(直径小于10nm)也能做到有效吸附,有望成为超级吸附与过滤材料。