CuInS2纳米晶的制备及三阶非线性光学性质的研究

以无水醋酸铜(Cu(AC)2)为铜源,氯化铟(InCl3)为铟源,正十二硫醇(DDT)为硫源,1-十八稀(ODE)为溶剂在240℃条件下反应3h,合成了金字塔形的CuInS2纳米晶。用X射线粉末衍射(XRD),X射线光电子能谱(XPS),透射电子显微镜(TEM),能量分散光谱(EDS),Z-Scan技术对粉体的结构、形貌、相组成、三阶非线性光学特性进行表征。结果表明:通过一锅法可以合成单分散颗粒尺寸为5-7nm的金字塔形CuInS2纳米晶;分散在正己烷中的CuInS2纳米晶的三阶光学非线性折射率γ,三阶光学非线性吸收系数β以及三阶光学非线性极化率χ(3)分别为3.444×10-17m2/W,4.526×10-7m/W和1.390×10-8esu。     

低温下铜纳米颗粒对UHMWPE复合材料摩擦磨损性能影响

向碳纤维(CF)与聚苯酯(POB)增强超高分子量聚乙烯(UHMWPE)复合材料加入不同质量分数铜纳米颗粒,探究了加入铜纳米颗粒对复合材料的力学性能与导热性能的影响.使用扫描电子显微镜(SEM)对铜纳米颗粒改性复合材料在低温环境下时磨损微观表面进行观察.使用原子力显微镜(AFM)研究了低温环境下改性复合材料转移膜的形貌.研究表明:低温环境下该改性复合材料摩擦因数和磨损率低于室温环境下的摩擦因数和磨损率.低温环境下改性复合材料磨损机理以疲劳磨损和磨料磨损为主,加入铜纳米颗粒后形成致密且连贯的转移膜,显著降低了改性复合材料的磨损率.     

钨铜与纳米钨铜复合材料的发展现状

高导电导热性铜与高温强度、强抗电弧烧蚀钨的良好结合使钨铜复合材料具有一系列优异性能。钨与铜的互不相溶性决定了钨铜复合材料制备的特殊性。由于纳米颗粒具有特殊性能和很大的活性，纳米钨铜复合材料的制备尤为特殊。本文作者介绍了近年来国内外钨铜复合材料及纳米钨铜复合材料的研究现状，总结分析了其主要制备方法的特点和进行改进需要考虑的问题。     

SiCp/Cu复合材料热膨胀性能研究

以电子封装基片为应用背景,采用挤压铸造方法制备了体积分数为55％,不同颗粒粒径增强的SiCp／Cu复合材料,并分析测试了颗粒粒径和热处理状态对材料热膨胀性能的影响规律．显微组织观察表明,复合材料颗粒分布均匀,材料组织致密;热膨胀性能测试表明,随着温度升高,复合材料的热膨胀系数呈非线性增加;SiC体积分数相同时,减小SiC颗粒尺寸有利于降低复合材料的热膨胀系数;退火处理可以减小基体中的热残余应力,有助于降低复合材料的热膨胀系数．     

新技术实现纳米粒子薄膜1min完成自我装配

正美国能源部劳伦斯·伯克利国家实验室的研究人员改进了一种技术,使得自我装配的纳米粒子阵列能够在1min内在肉眼可见的尺寸内形成高度有序的薄膜。研究人员将基于嵌段共聚物的超分子与金纳米颗粒相结合,制造出一种纳米复合材料。金纳米颗粒在经过溶剂退火处理后会迅速自我装配并形成分层级的结构薄膜,面积达到平方厘米级,厚度约为200nm。该技术可与当前的纳米加工过程(如刮涂、沉积等)兼容,具有形成新光学涂膜以广泛用于太     

退火温度对Nd4.2Dy0.8Pr4Fe85Nb1B5纳米复合材料磁性能的影响

用熔体快淬和晶化处理的方法制备了Nd4.2Dy0.8Pr4Fe85 Nb1B5纳米复合材料,研究了退火温度对材料磁性能的影响.结果表明,经不同退火温度进行退火处理得到的Nd4.2 Dy0.8Pr4Fe85Nb1B5纳米复合材料的磁性能不同,在580℃下退火处理3 min得到的样品具有最佳磁性能,即Hci=6787.0 ...     

基于纳米纤维的光学折射率传感器研究

利用纤维进行光学传感是目前较热门的研究领域,纤维系统的光学传感可以用来检测环境中的压力、温度、湿度、浓度以便探究事物之间的相互联系.提出了一种基于纳米纤维的折射率传感器,可以检测周围折射率的局部变化.此外,还给出了直接求解电磁问题的方法,该方法证明了纳米纤维的几何形状可以探测局部折射率.最后,对此现象的机制和检测局限性进行了讨论.     

银纳米颗粒-玻璃复合薄膜的三阶非线性光学性能

采用离子交换结合热处理方法,制备出银纳米颗粒-玻璃复合薄膜.利用光学吸收谱和Z-扫描技术研究了该复合薄膜的线性和三阶非线性光学性能.研究结果表明,延长热处理时间有利于提高银纳米颗粒尺寸和银纳米颗粒在玻璃中的体积分数,导致复合薄膜的三阶非线性系数增大.当熔盐中AgNO3/NaNO3的质量分数由0.1%提高到0.5%时,相同条件热处理后玻璃中银纳米颗粒的尺寸和体积分数有较大增长,复合薄膜的三阶非线性系数增大;进一步提高熔盐中AgNO3/NaNO3的质量分数,热处理后玻璃中银纳米颗粒的尺寸反而降低,但银纳米颗粒在玻璃中的体积分数增大,材料的三阶非线性系数不增反降.     

纳米金刚石核/洋葱状碳壳材料的可见光光催化活性研究

对纳米金刚石退火后得到的核为金刚石/壳为石墨烯的复合材料(其曾表现出优异的吸附和光催化能力)进行了研究。结果表明：对粗颗粒(粒度为50 nm)的纳米金刚石进行高温退火处理,金刚石表面会石墨化,但不会形成洋葱石墨壳层;退火后的纳米金刚石也不具有对甲基橙溶液的光催化降解能力。采用爆轰法制备纳米金刚石(粒度为5 nm),并在高温(1 400～1 500℃)退火下获得了核/壳结构的纳米金刚石/洋葱状碳材料。研究发现：该复合材料具有良好的可见光光催化活性,经1 500℃退火的纳米金刚石在1 h内可让浓度为100mg/L的甲基橙溶液几乎完全降解。     

金银纳米颗粒的制备和表征及其掺杂玻璃三阶非线性研究进展

贵金属金银纳米颗粒具有许多独特的物理、化学性质,其广泛应用于催化、能源、光电子和生物等领域.介绍了金银纳米颗粒的各种制备方法及表征,并综述了金银纳米颗粒掺杂玻璃的三阶非线性光学性质及研究进展.     

铜颗粒分散铌酸钾钠压电复合材料的制备与性能

在工业氮气(N2)气氛条件下制备了锂掺杂铌酸钾钠/铜(NKLN/Cu)压电复合材料,研究了铜含量对复合材料的相结构、密度、电学性能及力学性能的影响。结果表明:复合材料由NKLN陶瓷相和Cu金属颗粒两相组成,不同Cu含量复合材料的相对密度均达到95%以上。复合材料的介电常数随Cu含量的增加而急剧增加,压电常数和机电耦合系数随Cu含量的增加而减小,当Cu的体积分数达到20%时,NKLN/Cu复合材料的介电性能和压电性能均难以测量。NKLN/Cu复合材料的显微硬度随Cu含量的增加而降低,断裂韧性值随Cu含量的增加而升高,从铌酸钾钠陶瓷的1.01 MPa逐渐增至Cu的体积分数为40%时的2.81 MPa。     

SiCp/Cu复合材料高温抗氧化性能研究

采用粉末冶金方法制备了SiCp/Cu复合材料,研究了复合材料在恒温氧化和循环氧化条件下的抗氧化性能。结果表明：在400—700℃时,SiCp/Cu复合材料具有比纯铜优良的抗氧化性能;在温度一定的条件下,SiC体积分数为20%时,复合材料的抗氧化性能最好;在循环氧化条件下,随着氧化时间延长,复合材料氧化增重率逐渐增大,而且呈现近抛物线变化规律;对相同SiC颗粒含量的SiCp/Cu复合材料,SiC颗粒越细,试样的抗氧化性能越好。     

Tribological properties of SiC/Cu composite at high temperature

SiC/Cu composites were prepared by hot pressing. The high temperature tribological properties of the composites were investigated. XRD, SEM techniques were carried out to characterize the samples. It is found that the friction coefficient of SiC/Cu composites increases with the increasing SiC content. The SiC reinforcement particles are worn down other than removed by pulling out during the wear test. Oxidation of Cu debris leads to the smooth contacting surface. Ring crack is formed under the cyclic wear test. The crack propagates through the damaged matrix and along the brittle interface between SiC particles and Cu matrix.     

Microstructure and thermal properties of SiCp/Cu composites with Mo coating on SiC particles

SiCp/Cu composites with a compact microstructure were successfully fabricated by vacuum hot-pressing method. In order to suppress the detrimental interfacial reactions and ameliorate the interfacial bonding between copper and silicon carbide, molybdenum coating was deposited on the surface of silicon carbide by magnetron sputtering method and crystallized heat-treatment. The effects of the interfacial design on the thermo-physical properties of Si Cp/Cu composites were studied in detail. Thermal conductivity and expansion test results showed that silicon carbide particles coated with uniform and compact molybdenum coating have improved the comprehensive thermal properties of the Si Cp/Cu composites. Furthermore, the adhesion of the interface between silicon carbide and copper was significantly strengthened after molybdenum coating. Si Cp/Cu composites with a maximum thermal conductivity of 274.056 W/(m·K) and a coefficient of thermal expansion of 9 ppm/K were successfully prepared when the volume of silicon carbide was about 50%, and these Si Cp/Cu composites have potential applications for the electronic packageing of the high integration electronic devices.     

Effect of Cu-Ti-C Reaction Composition on Reinforcing Particles Size of TiC_x/Cu Composites

TiC_x/Cu composites were fabricated by combustion synthesis and hot press technology. Using XRD, SEM, EDS, FESEM analysis methods, the effects of various carbon sources and different Cu contents on the microstructures of TiC_x/Cu composites and the size of TiC_x particles were investigated. Results showed that TiC_x reinforcing particles size increases with decreasing Cu content in Cu-Ti-C reaction system. With carbon nanotubes(carbon black) serving as carbon source, the generated TiC_x particles size transits from nanometer to submicron when Cu content corresponding to the reaction system is reduced to 60 vol%(70 vol%); while graphite serves as carbon source, there is no clear limiting concentration. C particles with smaller size, larger specific surface area and better distribution result in finer TiC_x particles, which is more beneficial to generating nano-sized TiC_x/Cu composites.     

A novel technique for preparation of electrically conductive ABS/Cu polymeric gradient composites

A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes’ law. Acrylonitrilebutadiene-styrene/Cu (ABS/Cu) gradient polymeric composites were prepared successfully using this technique. The gradient structures, electrically conductive performance and mechanical properties of the ABS/Cu composites were investigated. Optical microscope observation shows that the gradient distribution of Cu particles in ABS matrix was formed along their thickness-direction. The electrically conductive testing results indicate that the order of magnitude of surface resistivity was kept in 10₁₅ Ω at ABS rich side, while that declined to 10⁵ Ω at Cu particles rich side, and the percolation threshold was in the range of 2.82 vol%–4.74 vol% Cu content at Cu particles rich side. Mechanical test shows that the tensile strength reduced insignificantly as the content of Cu increases owing to the gradient distribution.     

Synthesis of Ag@Cu_2O core-shell metal-semiconductor nanoparticles and conversion to Ag@Cu core-shell bimetallic nanoparticles

Ag@Cu2O core-shell metal-semiconductor nanoparticles(NPs) were prepared by using solution phase strategy. It was found that Ag@Cu2O core-shell NPs were easily converted to Ag@Cu bimetallic core-shell NPs with the help of surfactant PVP and excessive reducer ascorbic acid in air at room temperature, which is a unique phenomenon. Varying volumes of Ag colloidal solutions were added into the reaction mixtures containing fixed initial concentrations of Cu2+ and PVP, Ag@Cu2O and Ag@Cu core-shell NPs with fixed core size but varying outer shell thicknesses could be obtained. The composites, structures, morphologies and extinction properties of Ag@Cu2O and Ag@Cu core-shell NPs were systematically characterized by XRD, TEM and extinction spectra. Both of these NPs show wide tunable optical properties. The extinction peaks could be shifted from 421 nm to 700 nm. FTIR results reveal that Cu+ ions on the surface of Cu2 O nanocrystalline coordinate with N and O atoms in PVP and further are reduced to metallic Cu by excessive ascorbic acid and then form a nucleation site on the surface of Cu2 O nanocrystalline. PVP binds onto a different site to proceed with the reduction until all the Cu sources in Cu2 O NPs are completely assumed. And the shell of Cu2 O is converted to Cu shell. The synthesis approach in this paper is simple and also a promising reference for synthesizing other core-shell NPs. Ag@Cu2O NPs can be easily converted to Ag@Cu NPs in air at room temperature, which is promising to be used in electronic devices.     

Hierarchical Co_3O_4 Microstructures Decorated with Ag and Cu Oxides: Study of Photocatalytic and Electrochemical Properties

Three-dimensional hierarchical Co_3O_4 microstructures decorated with Ag and Cu oxides were prepared via displacement reaction and subsequent annealing treatment.Photocatalytic properties measurements revealed that the photocatalystic activities of Cu O/Co_3O_4 composites(Co_3O_4 microstructures decorated with Cu O)were enhanced while those of Ag_2O/Co_3O_4 composites(Co_3O_4 microstructures decorated with Ag_2O)were reduced,when compared with those of pure hierarchical Co_3O_4 microstructures toward the degradation of methyl orange.In addition,Cu O/Co_3O_4 composites exhibited an excellent recyclability ability of photodegradation.The electrochemical properties test indicated that both of the composite oxide electrodes exhibited excellent pseudocapacitive performance with relatively high specific capacitance and good long-term cycling stability.With the increase of the loaded Ag_2O and Cu O dosages deposited on the Co_3O_4 microstructures surface,the specific capacitance values of the composites were increased.Ag_2O/Co_3O_4 composite electrodes showed higher specific capacitance values and better cycling stability than Cu O/Co_3O_4 composite ones.     

纳米颗粒弥散强化铜基复合材料的显微组织与性能

采用粉末冶金的方法,以Al2O3,SiO2,SiC和MgO等纳米颗粒为增强相,制备出4种不同颗粒的纳米复合材料,研究了各增强相对复合材料显微组织与性能的影响.结果表明:在相同的质量分数(ω)和制备工艺下,不同弥散相颗粒的弥散强化铜合金显微组织不同,铜基体上大体均匀地分布着细小的弥散相颗粒,但部分区域仍存在偏聚现象.4种复合材料的电导率相近,抗拉强度方面Cu/Al2O3与Cu/SiO2的性能要略好于Cu/SiC与Cu/MgO.     

Properties, phases and microstructure of microwave sintered W-20Cu composites from spray pyrolysiscontinuous reduction processed powders

The effects of microwave sintering on the properties, phases and microstructure of W-20Cu alloy, using composite powder fabricated by spray pyrolysis-continuous reduction technology, were investigated. Compared with the conventional hot-press sintering, microwave sintering to W-20Cu composites could be achieved with lower sintering temperature and shorter sintering time. Furthermore, microwave sintered W-Cu composites with high densification, homogenous microstructure and excellent properties were obtained. Microwave sintering could also result in finer microstructures.