不同离子激活的ZrO2纳米粉发光性质的研究

采用均相沉淀法制备出四方相氧化锆(t-ZrO2)纳米晶,引入不同类型的激活离子(包括稀土离子、过渡金属离子及其他典型的掺杂离子),采用单掺及共掺的方式系统的研究了掺杂ZrO2纳米晶的发光,并对不同的离子掺杂浓度及不同的合成温度对掺杂的ZrO2纳米晶发光性质的影响进行了阐述.     

Ni-ZrO_2纳米复合镀层在结晶器中的应用

文章对Ni-ZrO2纳米复合镀层的性质进行实验室研究,Ni-ZrO2纳米复合镀层由金属镍以及弥散分布于其中的高硬度ZrO2纳米微粒构成,该纳米复合镀层具有高硬度、高耐磨性、良好的耐高温性能以及低内应力等特点。实验结果证明使用效果要比电镀铬镀层有了大幅度提高。     

静电纺丝制备的ZrO2纳米纤维及其应用的研究进展

制备超细、高性能ZrO2纤维是实现其在催化、能源及环境等领域工程应用的关键。静电纺丝技术是一种近年来兴起的氧化物陶瓷纳米纤维制备新方法,能够制备直径较小、均一性高、连续性好的ZrO2纳米纤维,并且可通过控制前驱体纺丝液组成、静电纺丝工艺及热处理参数,对ZrO2纤维的组成、结构及性能进行调控。介绍了ZrO2纳米纤维制备、结构及性能方面的研究进展,并对经由原料组成、静电纺丝工艺及热处理条件调控的ZrO2纳米纤维结构、性能以及应用进行了综述和分析。     

纳米氧化锆的制备新工艺研究

以ZroCl2·8H2O和H2O2为原料,采用中和沉淀法制备纳米氧化锆,在制备工艺过程中2次(前驱体制备过程和研磨过程)加入分散剂(表面活性剂)来抑制粉体的团聚.探讨了有关因素对制备氧化锆产品的影响,例如前驱体氢氧化锆的煅烧温度对氧化锆晶型的影响,表面活性剂对产品粒径的影响,煅烧时间对ZrO2平均粒径的影响,研磨助剂对ZrO2平均粒径的影响等,研究得到了最佳工艺条件,并在优化实验条件下制备出平均粒径为50nm、粒径分布均匀的球形纳米氧化锆粉末.     

金属离子掺杂TiO2的光催化性能研究

用醇盐水解法制备了Ce4+、Ag+、Fe3+、Fe2+、Sn4+、Zn2+、Mo6+等金属离子掺杂的TiO2复合微粒.以罗丹明6G降解为目标反应,研究了所制备的复合微粒光催化活性与选择性.并用IR、XRD、TEM及BET等技术,对TiO2复合微粒进行了表征.结果显示在TiO2内掺入Ce4+、Ag+、Sn4+,可使纳米TiO2的光催化活性增强,而Fe3+、Fe2+、Zn2+、Mo6+等金属离子掺杂的二氧化钛复合微粒的催化活性呈下降趋势.     

电沉积Ni-Mo/ZrO2合金镀层结构及其电化学性能

为提高Ni-Mo合金镀层的电化学性能,在Ni-Mo镀液中添加纳米ZrO2颗粒成功制备了Ni-Mo/Zr02复合镀层,研究了Ni-Mo/ZrO2合金电镀层的结构及其化学活性,并与Ni-Mo、Ni/ZrO2的相关性能进行了对比.研究结果表明:Ni-Mo/ZrO2镀层结构为非晶+纳米晶并混杂有ZrO2纳米颗粒,添加ZrO2纳...     

电沉积Ni-W非晶态合金复合镀层研究

研究了在Ni－W非晶态合金镀液中加入ZrO2纳米微粒后的电沉积工艺,得到工艺参数与非晶态复合镀层的成分、结构和镀层在面形貌的关系。加入ZrO2纳米微粒后,提高了Ni-W非晶态复合镀层的高温抗氧化性能和硬度。     

湿化学法制备氧化锆超滤膜及其表征

以湿化学法制备的纳米氧化锆晶粒悬浮液为原料,在管式陶瓷微滤膜上制备了ZrO2超滤膜,用TEM考察了ZrO2晶粒悬浮液的性质,用N2吸附-脱附法和SEM对膜的结构、形貌与孔径分布进行了表征,考察了氧化锆悬浮液的浓度对膜的完整性的影响,并用不同分子量的葡聚糖对膜的截留性能进行了考察.实验表明:用该方法制备出的ZrO2膜完整无缺陷,孔径在16 nm左右,对葡聚糖的截留分子量为42 000 Da.     

反相胶束法制备纳米ZrO2粉体

利用NA/煤油-n-C6-OH/NH3@H2O反胶束体系,制备了纳米ZrO2粉体.采用TG-DTA、TEM、XRD等手段对粉体及前驱体进行表征粉体粒度分布均匀,无硬团聚,平均粒度为20～40nm.并且研究了反相胶束中的溶水量对ZrO2粒径的影响以及pH值对ZrO2晶型的影响.并推测20～40nmZrO2的单斜晶(m)与四方晶(t)可能的相转变温度为723℃,比相应的体相材料降低了近450℃.     

ZrO2-膨化石墨/焦炭复合材料的结构和制备

运用两种不同技法制备了ZrO2纳米粒子改性的膨化石墨/焦炭复合材料,应用XRD、SEM和TEM对所得ZrO2改性炭材料进行了表征.技法1:在ZrO(NO3)2及NH4OH溶液中反复交替地浸渍低密度膨化石墨/焦炭块体,随后在1200℃氮氛中热处理,以使在炭块自由表面沉积ZrO2纳米粒子的薄层.技法2:将可膨胀石墨、酚醛树脂粉和ZrOC2 O4-改性的纤维素纤维混合物封装于一容器中,使之经受900℃热激震,随后在氮氛中1200℃热处理,获得改性复合材料.结果表明:复合材料中ZrO2纳米粒子呈现三种尺寸:6nm～30nm为单独的纳米粒子和小微粒;200nm～1000nm为长树突状结构物;1μm～40μm为形如纤维素前驱体的杆状物.     

电解质和酸碱性对天然鲜胶乳电动特性的影响

采用高速冷冻离心处理天然鲜胶乳制备离心胶乳,通过改变胶乳中酸碱度和电解质,结合激光多普勒技术、扫描电子显微镜以及电感耦合等离子体质谱仪等仪器对处理前后的胶乳进行电动特性、形貌及金属离子含量分析。结果表明pH值的降低能使胶乳电泳迁移率的正负发生反转。增加电解质浓度,天然鲜胶乳负的电泳迁移率随之降低,相同浓度条件下阴离子电解质对天然胶乳电泳迁移率与电导率的影响顺序为NaClNaBrNaNO3SDS(十二烷基硫酸钠)。金属阳离子压缩天然胶乳双电层效率由大到小依次为Al 3+Fe3+Fe2+Cu2+Mn2+Co2+Ca2+Na+。高价金属阳离子如铜离子、铁离子与铝离子能使胶乳带电性质反转,酸碱度及形貌分析表明这些电解质会改变胶乳pH值环境,使胶乳发生团聚甚至破乳现象。     

Precipitation of cetyl (hexadecyl) pyridineum chloride using mono and divalent oxyanions

Experimental investigations have been carried out to observe the performance of precipitation behavior of potassium permanganate (KMnO₄) and potassium dichromate (K₂Cr₂O₇) in cetyl (hexadecyl) pyridineum chloride (CPC) solution. As in the case of Al³⁺-dodecylbenzenesulfonate systems [P. Somasundaran, K.P. Anathapadmanabhan, M.S. Celik, Langmuir 4 (1988) 1061–1063], the precipitation is found to be caused by interaction of CPC micelles with oxyanions. The counter oxyanions have a strong tendency to bind themselves to the surface of cationic CPC micelles. This lowered the free oxyanion concentration in solution. Therefore, to start precipitation, higher oxyanion concentration is required for higher CPC concentration. The effects of temperature, concentrations of both counter ions and CPC on the precipitation have been studied in detail. It has been observed that at CPC to KMnO₄ concentration ratio of 1.0 (concentration of CPC and KMnO₄ is 400 ppm), the percentage precipitation of CPC is around 99.3 at 30 °C. The percent precipitation of CPC decreases to about 94% when temperature increases to 70 °C at the same condition. The extent of CPC precipitation increases at the same experimental condition when K₂Cr₂O₇ is used instead of KMnO₄.     

Effects of Nitrogen Concentration on Microstructure and Antibacterial Property of Copper-Bearing Austenite Stainless Steels

Austenite antibacterial stainless steels have been found to have wide applications in hospitals and food industries. In recent years epsilon copper precipitation in antibacterial stainless steels has obtained much research interest due to its antibacterial action. The objective of this study was to determine the effects of nitrogen concentration on the precipitation of epsilon copper and antibacterial property. Two kinds of austenite antibacterial stainless steels containing copper and different nitrogen concentration （0.02 and 0.08 wt pct, respectively） were prepared and the microstructures were characterized by a combination of electron microscopy and thermodynamic analysis. A mathematical expression was deduced to predict the effect of nitrogen concentration on the activity coefficient of copper, In（fCu/f^0cu）=0.53524＋4.11xN-0.48x^2N. Higher nitrogen was found to increase the free energy difference of copper concentration distribution between precipitation phase and austenite matrix, stimulate the aggregation of copper atoms from austenite, increase the precipitation amount and consequently enhance the antibacterial property of steel.     

单分散球形MoS2超细粉体材料的制备

采用液相沉淀-高温氢还原两步合成新方法制备单分散球形MoS2超细粉体材料,利用透射能谱、X射线衍射仪(XRD)、冷场扫描电子显微镜(SEM)和马尔文激光粒度仪等研究了反应条件对产物化学组成、晶型的影响以及酸浓度、熟化时间和反应温度对前驱体MoS3平均粒径的影响.研究结果表明:反应条件对 前驱体MoS3的晶型没有影响;M...     

Influence of the Atmosphere on Optical Systems

The main effects of atmospheric absorption, scattering and turbulence on the propagation of visible and infra-red radiation are presented with particular emphasis on their wavelength dependence. Meteorological factors such as the concentration of molecular absorbers and the size distribution of scattering centres in precipitation are introduced and, from such data, typical attenuation figures are estimated. The main theoretical and experimental results concerning propagation in the turbulent atmosphere are summarized. The influence of the above effects on optical instruments and communication systems is examined. In the first category are included such instruments as radiometers and image-forming systems. In the latter section we consider the extent to which the performance of unguided communication systems would be degraded by adverse meteorological conditions.     

直接沉淀法制备纳米ZnO

以ZnCl2 为原料 ,直接沉淀法制备ZnO纳米粒子 ;研究了制备过程中Zn2 + 浓度、焙烧温度等条件对ZnO纳米晶体粒径的影响 ,并对其机理进行了分析。实验结果表明 ,较小的反应浓度可以获得较小的晶体粒径 ;在其它反应条件相同的情况下 ,制备的纳米ZnO粒子 ,其晶粒尺寸随着焙烧温度的增加 ,晶粒逐渐增大 ,与体相ZnO粒子相比 ,纳米ZnO粒子在紫外区光吸收能力显著增强 ,为ZnO的应用开辟了更为广阔的前景。     

FeVO_4光催化剂降解甲基橙研究

实验采用液相沉淀法制备了三斜型FeVO4光催化剂,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等方法对样品结构和形貌进行分析和表征,在40W紫外灯(主波长为253.7nm)照射下降解一定浓度的甲基橙溶液,研究其对甲基橙溶液降解效果.研究了催化剂用量、甲基橙初始浓度、光强度及pH值对甲基橙降解率的影响.     

CeO2纳米棒的微波合成及其光催化性能

采用微波均相法制备具有光催化活性的CeO2纳米棒,用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、比表面积与孔径分布测试(BET-BJH)以及紫外-可见吸收光谱测试(UV-vis)等手段对其进行表征,研究了尿素浓度对晶粒尺寸、形貌和光催化性能的影响,结果表明,当尿素浓度达到6.0 mol/L时产物的棒状...     

纳米ZnO的制备

本文研究了以Zn (No3 ) 2 、尿素为原料 ,加入表面活性剂改性制备纳米氧化锌粉体的方法。实验讨论了Zn (NO3 ) 2 浓度、尿素浓度、pH值、焙烧温度对纳米氧化锌粒径的影响。用扫瞄电镜和粒度分析仪确定纳米氧化锌的形貌和粒径     

Nonvolatile flexible organic bistable devices fabricated utilizing CdSe/ZnS nanoparticles embedded in a conducting poly N-vinylcarbazole polymer layer

The bistable effects of CdSe/ZnS nanoparticles embedded in a conducting poly N-vinylcarbazole (PVK) polymer layer by using flexible poly-vinylidene difluoride (PVDF) and polyethylene terephthalate (PET) substrates were investigated. Transmission electron microscopy (TEM) images revealed that CdSe/ZnS nanoparticles were formed inside the PVK polymer layer. Current-voltage (I-V) measurement on the Al/[CdSe/ZnS?nanoparticles+?PVK]/ITO/PVDF and Al/[CdSe/ZnS nanoparticles+?PVK ]/ITO/PET structures at 300?K showed a nonvolatile electrical bistability behavior with a flat-band voltage shift due to the existence of the CdSe/ZnS nanoparticles, indicative of trapping, storing and emission of charges in the electronic states of the CdSe nanoparticles. A bistable behavior for the fabricated organic bistable device (OBD) structures is described on the basis of the I-V results. These results indicate that OBDs fabricated by embedding inorganic CdSe/ZnS nanoparticles in a conducting polymer matrix on flexible substrates are prospects for potential applications in flexible nonvolatile flash memory devices.