Mn_3O_4纳米颗粒的制备及改性

研究了一种以低成本的硫酸锰为原料制备Mn3O4的方法,并成功制得纯相的纳米级Mn3O4。通过研究得到制备的最佳条件,反应温度为80℃,乙醇为表面活性剂,反应时间在1 h,然后150℃下煅烧。采用X射线衍射(XRD),透射电子显微镜(TEM)等手段进行了表征,产物粒子为纯相,平均粒径为50 nm以下。     

金属含量对Co-TiO2纳米颗粒复合薄膜微观结构及其性能的影响

目的使Co-TiO_2纳米颗粒复合薄膜同时具备高的磁化强度及电阻率,从而实现更好的高频软磁特性。方法通过磁控共溅射的方法,在不同金属靶功率下制备了Co-TiO_2纳米颗粒复合薄膜,并探究金属含量对薄膜的微观结构、表面形貌、电学和静态磁学性能的影响。结果薄膜中的金属颗粒被非晶态的TiO_2分散。金属含量的增加可以显著提高纳米颗粒薄膜中金属颗粒的结晶性,降低薄膜电阻率,并且通过改变金属含量,可使薄膜逐渐从超顺磁态向铁磁态转变,达到精确调控纳米颗粒复合薄膜的磁学和电学性能的目的。结论在金属含量达到54%时,实现了高电阻率和高饱和磁化强度共存,有望得到具有高频软磁特性的纳米颗粒复合薄膜。     

雷达隐身材料技术的发展

概述了雷达隐身技术,及雷达隐身材料的吸波原理,着重讨论了导电高分子吸波材料、纳米金属合金颗粒吸波材料技术的发展.     

The effect of pre-thermal treatment of TiO2 nano-particles on the performances of dye-sensitized solar cells

We have demonstrated the effect of pre-thermal treatment of TiO₂ nano-particles on the performances of dye-sensitized solar cells (DSCs) by using high specific surface area and anatase only TiO₂ nano-particles (ca. 340 m²/g, Sachtleben Chemie GmgH, represented as HK). TiO₂ particles and thin films were characterized with X-ray diffraction, FT-IR, UV–Vis diffuse reflectance spectroscopy and FE-SEM. The photoelectrochemical properties of the thin films and the performances of DSCs were measured by photocurrent densities, AC impedance spectra and photocurrent–voltage curves. Before coating the raw TiO₂ of HK (HK-raw) on transparent conducting oxide (TCO) glass for DSC fabrication, pre-thermal treatment of HK-raw by calcining at 450 °C (HK-450) was an essential step to achieve the optimum properties in terms of morphological feature, crystallinity, specific surface area and photocurrent density. HK-450 film showed the high adsorption of dye, high photocurrent density and low interface resistance between TiO₂ and TCO glass, R_TiO2/TCO and TiO₂ and redox electrolyte, R_CT, resulting in the superior photovoltaic performance on the DSC fabricated with HK-450 and Eosin Y (or ruthenium 535 bis-TBA) at AM 1.5: open-circuit voltage of 0.62 V (0.77 V), short-circuit current of 3.03 mA/cm² (22.80 mA/cm²), fill factor of 0.57 (0.44) and overall conversion efficiency of 1.06%, (7.52%). Accordingly, the optimization between the morphological feature, specific surface area and photocurrent density of TiO₂ substrate is promising to accomplish the improved overall conversion efficiency of DSC.     

纳米微粒增强镍基复合镀层的研究进展

综述了纳米微粒增强镍基复合镀层的研究进展。纳米微粒增强镍基复合镀层具有致密的组织结构和优良的综合性能,潜在应用前景广阔。解决目前纳米微粒增强镍基复合镀层制备中存在的难题,将推动纳米微粒增强镍基复合镀层的研究向深层拓展。     

超声法纳米颗粒悬浮液粒径测量中温度影响的实验研究

针对医药、化工领域高浓度纳米悬浮液颗粒粒径超声检测中温度影响,采用超声衰减谱法(UAS)对体积浓度30%的纳米铟锡金属氧化物(ITO)水性悬浮液在循环流速800 r/min,温度298～358 K时颗粒粒径分布进行实验。结果表明:温度升高,超声幅值A减小,超声衰减系数增大,颗粒中位径D50增大,颗粒系分布曲线整体朝大颗粒方向偏移,但是分布宽度保持稳定的趋势。同时,将室温(298K)测量结果与CPS离心沉降颗粒测量仪对比,结果较吻合。通过线性回归的方法修正温度对测量结果的影响,超声衰减法能够应用于358K的高温下高浓度纳米颗粒检测。     

纳米TiN颗粒增强TiC-WC-Mo2C-Ni-Co金属陶瓷的组织和力学性能

纳米颗粒增强金属陶瓷材料具有优良的力学性能因而受到广泛关注。介绍了纳米颗粒增强金属陶瓷的实验制备、组织和性能,重点论述了微观组织中的芯/壳结构。研究表明,随着Mo2C添加量的增加,金属陶瓷的组织存在着变细的趋势。当Mo2C含量为10%时,金属陶瓷材料硬度出现最大值。     

纳米TiO2改性丝素膜中的纳米颗粒粒径分析

为了进一步改善丝素蛋白膜的结构性能,尝试用溶胶凝胶法制备纳米TiO2改性丝素复合膜。测得用溶胶--凝胶法在丝素溶液中直接生成的纳米粒子粒径在76 nm左右,用AFM、有效质量近似模型估算出纳米改性再生丝素膜中纳米粒子粒径在80 nm左右; 当TiO2含量小于1.2 %时,生成的纳米粒子的尺寸小于100 nm;纳米粒子尺寸随着溶液pH的增加而增大。研究表明用溶胶-凝胶法制备纳米再生丝素膜方法可行,成膜前后纳米粒子没有发生团聚,都处于纳米级别。     

电子束辐照制备纳米镍

在水溶液中,常温常压下不加入任何催化剂,用电子束加速器辐照作为一种新的方法可成功制备纳米镍。利用X射线衍射(XRD)、透射电子显微镜(TEM)、激光衍射粒度分布仪(LSPSDA)、紫外可见光分光光度计(UV)、样品振荡磁力计(VSM)和差热分析仪(DSC)来分别表征材料的结构、形貌、大小、粒径分布、光学特征、磁学性能以及材料的熔点。TEM图像和LSPSDA分布图证明颗粒大小为39nm,这与XRD实验通过Scherer理论公式计算的结果相一致。     

Preparation and activity of carbon-supported porous platinum as electrocatalyst for methanol oxidation

In this paper, we reported a novel electrocatalyst, Vulcan XC-72-supported porous platinum nano-particles (Pt_p/C) for methanol oxidation. In the preparation of Pt_p/C, platinum precursor was first adsorbed on carbon and then reduced by l-ascorbic acid in ethylene glycol solution. The structure and morphology of Pt_p/C and its activity toward methanol oxidation were characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) measurement, X-ray diffraction (XRD), energy-dispersion spectrometer (EDS), cyclic voltammetry (CV), and chronoamperometry (CA), with a comparison of the electrocatalyst prepared with sodium borohydride as reducer (Pt_s/C). It is found that both electrocatalysts have similar particle size but have different surface morphology of platinum and thus exhibit different electrocatalytic activity toward methanol oxidation. The platinum particle size of both electrocatalysts is 3–5 nm, but the corresponding BET surface areas are different significantly, 131.6 m² g⁻¹ and 87.7 m² g⁻¹ for Pt_p/C and Pt_s/C, respectively, indicative of the porous structure of platinum particles in Pt_p/C. The peak current for methanol oxidation on CV is 167 mA mg⁻¹ and 44 mA mg⁻¹ for Pt_p/C and Pt_s/C, respectively, indicative of the high electrocataytic activity of Pt_p/C toward methanol oxidation. The result from CA shows that Pt_p/C has good stability as the electrocatalyst for methanol oxidation.