硫化镉纳米粒子的制备研究

利用直接溶液滴定法和以水玻璃体相制备硫化镉球形纳米粒子和针状粒子。通过扫描电镜、X射线衍射分析了所得样品的形貌和物相,结果表明所制备的硫化镉纳米粒子为球形和针状,其中,球形样品结晶程度低,部分样品被氧化,针状样品为纤锌矿型结构。     

苯乙烯-马来酸酐共聚物/氧化锌纳米粒子合成与表征

以N,N-二甲基甲酰胺为溶剂,乙酸锌为前驱物,苯乙烯-马来酸酐共聚物为大分子稳定剂,采用溶液化学法,制备了氧化锌纳米粒子。通过紫外-可见吸收光谱(UV-Vis)、荧光光谱(PL)、透射电子显微镜(TEM)等方法对合成的ZnO纳米粒子样品进行表征。结果表明,所合成样品具有量子尺寸效应,样品UV-Vis吸收光谱在350nm给出氧化锌纳米粒子的特征吸收峰,样品PL光谱显示在410nm处可产生明显的荧光发射。氧化锌纳米粒子的尺寸在50~100nm且粒径分布较窄,表明苯乙烯-马来酸酐共聚物对氧化锌纳米粒子的表面起到了良好稳定作用。     

炭黑与大小橡胶粒子的相互作用及其受停放时间的影响

采用反复离心纯化的方法制备出大、小橡胶粒子的胶乳样品,干燥得到天然橡胶生胶,与炭黑混炼得到相应混炼胶,研究了各样品与炭黑的相互作用及其随停放时间的变化。研究表明,小橡胶粒子胶乳所制备的天然橡胶相应混炼胶中结合胶含量较高,随停放时间延长,添加了小橡胶粒子的样品结合胶含量先上升后下降,大橡胶粒子样品结合胶含量则持续上升;扫描电子显微镜的分析结果表明,小橡胶粒子胶乳所制备的天然橡胶中炭黑分散性差,炭黑与橡胶基体相容性差,存在较多附聚体,大橡胶粒子胶乳所制备的样品中炭黑分散性则较优。差示扫描量热仪对结合胶玻璃化转变特性的分析表明,各结合胶样品在玻璃化转变前后的比热流差值随停放时间的延长先增大后减小,这是由于样品中的橡胶连续相先增加后减少。总而言之,小橡胶粒子胶乳所制备的天然橡胶相应混炼胶中所测结合胶含量更高,但与炭黑相容性差,多为受限于填料内部的包覆橡胶。     

CH与聚变材料Be相互作用的分子动力学模拟

采用分子动力学方法模拟了不同能量的CH粒子与聚变材料Be的相互作用。根据托卡马克中的环境,入射粒子CH的模拟入射能量分别设定为低能量(1,5,10,25 eV)和高能量(50,100,150,200 eV),其中碳的沉积率随能量的增大逐渐增加,而氢的沉积率恰好相反。当CH粒子的入射能量为低能量时,Be样品表面形成一层碳氢膜;且其膜厚度越来越薄,并且形成一个厚度逐渐增加中间层;当入射能量为高能量时,样品中的Be原子溅射越来越大,入射粒子在样品中的入射深度越来越深,对样品的破坏越来越大,且会在样品中形成一个C反应层。     

利用定量PCR方法研究对虾白斑杆状病毒感染与发病的关系

收集了6批共134尾不同感染程度的对虾样品,测定其WSBV含量。检测结果表明,无病症的对虾样品每毫克样品所携带的病毒量低于10^3个病毒粒子,有病灶的对虾样品每毫克组织所携带的病毒量均高于10^3个病毒粒子,根据这一结果,初步确定了疾病爆发的危险临界值为每毫克组织含10^3个病毒粒子。     

影响SiO_2薄膜中银粒子发光强度的因素分析

用ｓｏｌ－ｇｅｌ法在玻璃表面制备了含银纳米粒子的二氧化硅薄膜．拍摄了银粒子的ＴＥＭ照片．在室温下用拉曼光谱仪测定了样品的光致发光谱．研究了样品的光致发光强度与纳米银的掺杂量、镀膜时的提拉速度和热处理温度之间的关系．     

注Mn GaAs的铁磁性质

我们通过超导量子干涉仪对样品的测量发现样品在室温下依然显示出清晰的磁滞回线,进一步证实了样品在室温下具有磁性,并证明铁磁性来源于退火后生成的MnAS、MnGa磁性粒子。     

聚乙烯吡咯烷酮表面修饰氧化锌纳米粒子的合成与表征

以N,N-二甲基甲酰胺为溶剂,乙酸锌为前驱物,聚乙烯吡咯烷酮为表面修饰剂,采用溶液化学法,制备了氧化锌纳米粒子。通过紫外-可见吸收光谱(UV-Vis)、荧光光谱(FL)和透射电子显微镜(TEM)等方法对合成的氧化锌纳米粒子进行表征。结果表明:所合成样品具有量子尺寸效应,样品UV-Vis吸收光谱在335~350 nm给出了氧化锌纳米粒子的特征吸收峰;FL光谱显示在400,550 nm处产生荧光发射;氧化锌纳米粒子的尺寸在100 nm左右且粒径分布较窄,表明聚乙烯吡咯烷酮对氧化锌纳米粒子的表面起到良好的修饰作用。     

聚氨酯/环氧树脂乳胶互穿聚合物网络的制备和表征

以甲苯二异氰酸酯、聚丙二醇和环氧树脂为主要原料,合成了聚氨酯(PU)/环氧树脂(EP)乳胶互穿聚合物网络(LIPN)。红外分析表明,样品中PU与EP各自的交联网络均已形成,且二者之间不存在化学键的结合;用TEM和粒度分析仪观察样品的乳胶粒子形貌和尺寸大小,样品未呈现核壳结构,且与PU乳液空白样品的乳胶粒子形貌和尺寸基本一致。动态力学分析表明样品中两种组分在分子尺度互穿。力学性能分析表明二者表现出显著的协同效应。     

热解含硫金属有机配合物法合成亮紫色发光的α-ZnS:Cu纳米荧光粉

以硝酸锌、硝酸铜和二乙基二硫代氨基甲酸钠为原料,制得含硫金属有机配合物.将含硫金属有机配合物在200℃进行热解,制备了亮紫色发光的ZnS： Cu纳米荧光粉.XRD检测结果显示,荧光粉样品为六方晶系的高温相α-ZnS.根据TEM结果,样品为均匀的球形粒子,其粒子尺寸在30nm左右.室温下,样品的激发光谱峰值位于235nm...     

SiO_2@Ag核壳粒子表面形貌及壳层厚度影响因素的研究

用溶胶-凝胶法制备单分散的亚微米二氧化硅,经表面巯基化改性后,采用自组装化学镀法在其表面包Ag,得到SiO2@Ag核壳复合粒子,研究还原剂的种类、浓度和反应温度对核壳结构SiO2@Ag亚微米颗粒形貌及表面Ag壳层厚度的影响规律。结果表明:还原剂的种类对SiO2@Ag核壳复合粒子表面形貌影响较大,还原性太弱很难在二氧化硅表面形成致密均匀的银层,还原性太强则容易形成散银;还原剂浓度增加使二氧化硅表面银颗粒的粒径增大,银壳层厚度增大,但是当还原剂浓度到达一定的值后,浓度对银粒径大小和银壳厚度的影响变弱;反应温度对SiO2@Ag核壳复合粒子表面形貌也有较大影响,0~30℃时,银粒子随温度升高尺寸变大,银壳厚度也相应增大,若温度继续增加到50℃后则开始出现散银,包覆效果变差。     

Synthesis of silver chromate nanoparticles: Parameter optimization using Taguchi design

The Taguchi method of experimental design is very well suited to improving the production process of synthetic nanoparticles. The current application of the Taguchi method was successful in optimizing the experimental parameters affect on synthesis procedure of silver chromate nanoparticles. Ultrafine silver chromate particles were synthesied by precipitation method using addition of silver ion solution to the chromate reagent. The effect of reaction conditions such as: silver and chromate concentrations, flow rate of reagent addition and temperature on the particle size of synthesized silver chromate particles were investigated. The effect of these factors on the diameter of silver chromate particles were quantitavely evaluated by the analysis of variance (ANOVA). The results showed that silver chromate particles can be synthesized by controlling silver concentration, flow rate and temperature. Finally, the optimum conditions for synthesis of silver chromate particles by this simple and fast method were proposed. The results of ANOVA showed that 0.001 mol/l silver ion concentration, 40 ml/min flow rate for addition of silver reagent to the chromate solution and 0°C temperature are optimum conditions for producing silver chromate particles with 100 ± 33 nm width. On the other hand, the Ag₂CrO₄ nano-superstructures were synthesized by electrosynthesis method. The results showed that Ag₂CrO₄ nanoparticles synthesized by this method have 75 nm average diameter.     

Behavior of ultra fine silver-BaTiO3 composite powders at sintering

In this paper, the metal–ceramic composite material, i.e., silver–BaTiO3 composite powder, was prepared with chemical deposition method. Composition, dispersibility and shape of powder particles were investigated by XRD, SEM and size distribution analyzer. Coalescence of particles occurs during low sintering process, and sintering temperature has a great effect on composition and shape of single powder particles. The sintering of silver on the surface of particles increases with an increasing temperature by SEM and EDX observation. The shrinkage and softening temperature of composite powders increase and decrease as an increasing silver content, respectively, by TMA analysis. Sheet resistance 52 mΩ/□ was observed from the film corresponding to 80 wt.% silver content which was sintered at 300 °C.     

紫外光辐照双原位同步合成纳米Ag/PVP复合物的结构特征

在室温下,用紫外光辐照N-乙烯基吡咯烷酮(NVP)和硝酸银(AgNO3)水溶液,双原位一步合成了纳米银/聚乙烯吡咯烷酮(PVP)复合物。透射电镜(TEM)分析表明,纳米银/PVP复合物分散性好、粒径在5 nm左右;X射线光电子能谱(XPS)表明,C=O中C1s结合能(285.61 eV)比标准C=O中C1s结合能(287.79 eV)降低了2.18 eV,N1s的结合能比标准的能谱峰位(399.88 eV)降低了0.38 eV;红外光谱(FT-IR)表明,纳米Ag/PVP羰基吸收峰,峰位从1673 cm-1变化到1661 cm-1,发生红移;XPS和FT-IR分析表明,纳米银不仅和羰基氧有相互作用,而且通过p-π共轭效应,与氮和羰基碳也发生了相互作用。     

活性碳纤维载银工艺及其表面银颗粒的形态特征

以自制粘胶基活性碳纤维（ＡＣＦ）为载体，通过真空浸渍和真空热分解的方法在其表面沉积银，制得了载银活性碳纤维（ＡＣＦ（Ａｇ）。研究了载银工艺参数对ＡＣＦ（Ａｇ）的银含量、表面银颗粒大小、分布及形态的影响规律，提出了银颗粒的形核与长大机制；此外，还分析了银颗粒与ＡＣＦ结合力的影响因素。     

Electrical properties of silver paste prepared from nanoparticles and lead-free frit

Recently, PbO containing glass systems in commercial silver paste have been used due to their low glass transition temperature, good thermal and electrical properties. However, PbO is a hazardous material to both health and the environment. In this study, Pb-free silver paste was prepared by mixing commercial silver powder and silver nanoparticles. The commercial powder has an average particle size of 1.6 microm. The silver nanoparticles with particles size of 20-50 nm were synthesized by a chemical reduction method using surfactant. Pb-free frit was added into the mixed silver powder as the amounts of 3, 6 and 9 wt%. Using the obtained paste, thick films were fabricated by a screen printing on alumina substrate and the films were fired at temperature from 400 to 550 degrees C. The films had thickness of 6-11 microm and sheet resistivity of about 4-11 microomega cm.     

纳米银晶粒镶嵌氧化硅薄膜的光致发光

用SOL GEL法在浮法玻璃表面制备了掺杂纳米银晶粒的二氧化硅薄膜。在室温下测定了其可见光透过率和光致发光谱。研究了样品的光致发光强度与纳米银的掺杂量、镀膜时的提拉速度和热处理温度之间的关系     

微波辐射原位合成纳米银/聚苯乙烯复合乳液

在微波辐射下先还原金属前躯体AgNO3制备出纳米银胶体,再于水介质中原位聚合制备纳米银聚苯乙烯复合乳液,并对其进行了表征。紫外-可见吸收光谱、透射电镜结果表明,所制备出的纳米银大多为球形粒子,粒径为20~30nm,粒径分布窄,且分散性较好;红外分析表明,纳米银和过渡层PVP之间并非只是简单的物理混合,它们之间存在一定的化学键合;热失重分析表明,纳米银对聚合物的分解可能起催化作用,从而使得纳米银/聚苯乙烯复合粉末的分解温度比纯聚苯乙烯低。     

Size controllable synthesis of ultrafine silver particles through a one-step reaction

A simple one-step reduction method was explored to synthesize silver particles of different size. During synthesis, Polyvinylpyrrolidone (PVP) and CH₂O were used as the protective agent and the reducing agent, respectively. It is found that the reaction parameters including the concentration of PVP and AgNO₃, the amount of ammonia and the reaction temperature has great influence on the size and uniformity of silver particles. By careful tuning the reaction parameters, mono-disperse silver particles with the size of 40-2000 nm can be obtained controllably. It is considered that there were two growth modes: diffusional growth and aggregation.