热处理对氧化锌纳米线场发射特性的影响

用场发射显微镜研究了在钨针尖上生长的氧化锌纳米线的场发射性能,得到了氧化锌纳米线的场发射像及场发射电流与电压关系,并讨论了氧化锌纳米线场发射像的形成原因和不同热处理条件对其场发射性能的影响,给出了氧化锌纳米线比较合适的热处理温度.     

Grinding behavior of WO3, NiO,Fe2O3 by ultrasonic milling parameters control and preparation of nanocomposite powder

Tungsten-based alloys have been widely applied in various industries due to their excellent mechanical properties. Tungsten-based alloys have a high sintering temperature due to the high melting point of tungsten, so the coarse particles negatively affect the mechanical properties of the alloy. This problem can be solved by increasing the densification by reducing the sintering temperature and time by adding nanoparticles with high surface energy. Herein, we fabricated nanoparticle-sized metal oxides by ultrasonic milling to minimize the influx of impurities to improve the densification of tungsten alloys. The main parameters of the ultrasonic milling experiments were ball density and ball layer. Metal oxides prepared by ultrasonic milling showed an average particle size distribution of less than 200 nm, and metal composite powders prepared through subsequent hydrogen reduction also showed nanoparticle size distributions. We believe that this approach will enable the production of improved sintered tungsten-based alloys.     

Field emission characteristics of CuO nanowires by hydrogen plasma treatment

CuO nanowires were formed on copper-coated silicon substrates by a wet chemical process, immersing them in a hot alkaline solution. The effect of hydrogen plasma treatment on the field emission characteristics of the CuO nanowires was investigated. The results showed that hydrogen plasma treatment enhanced the field emission characteristics of the CuO nanowires showing a decrease in turn-on voltage as well as an increase of field enhancement factor. It is believed that hydrogen plasma treatment plays an important role in the improvement of field emission characteristics of CuO emitters.     

Localized Synthesis of Iron Oxide Nanowires and Fabrication of High Performance Nanosensors Based on a Single Fe2O3 Nanowire

A composed morphology of iron oxide microstructures covered with very thin nanowires (NWs) with diameter of 15–50 nm has been presented. By oxidizing metallic Fe microparticles at 255 °C for 12 and 24 h, dense iron oxide NW networks bridging prepatterned Au/Cr pads are obtained. X‐ray photoelectron spectroscopy studies reveal formation of α‐Fe₂O₃ and Fe₃O₄ on the surface and it is confirmed by detailed high‐resolution transmission electron microscopy and selected area electron diffraction (SAED) investigations that NWs are single phase α‐Fe₂O₃ and some domains of single phase Fe₃O₄. Localized synthesis of such nano‐ and microparticles directly on sensor platform/structure at 255 °C for 24 h and reoxidation at 650 °C for 0.2–2 h, yield in highly performance and reliable detection of acetone vapor with fast response and recovery times. First nanosensors on a single α‐Fe₂O₃ nanowire are fabricated and studied showing excellent performances and an increase in acetone response by decrease of their diameter was developed. The facile technological approach enables this nanomaterial as candidate for a range of applications in the field of nanoelectronics such as nanosensors and biomedicine devices, especially for breath analysis in the treatment of diabetes patients.     

Nanobelts,Nanowires, and Nanodiskettes of Semiconducting Oxides—From Materials to Nanodevices

Novel nanostructures of semiconducting oxides are reviewed here. It is shown that nanobelts, nanowires, and nanodiskettes of materials such as zinc oxide, gallium oxide, silica, and tin oxide can be fabricated using a vapor‐phase evaporation method. Two applications of these materials—in field effect transistors and as gas sensors—are highlighted.     

导电聚苯胺/纳米Fe3O4复合材料的制备及耐热性研究

采用原位聚合法制备了烷基苯磺酸掺杂的导电聚苯胺与纳米Fe3O4复合材料,并对纳米Fe3O4进行了XRD表征,经粉体激光粒度分布测试表明分散剂的存在能较好地保持纳米粉的分散.研究发现复合材料与导电聚苯胺比较,其热分解温度提高了100℃以上,而且分解速率大大下降,这主要是由于纳米Fe3O4粒子对烷基苯磺酸掺杂剂有强烈的表面吸附作用.     

磁性纳米CeO2/Fe3O4非均相Fenton反应催化降解氧氟沙星

为了提高Fe₃O₄的催化活性, 制备了磁性CeO₂/Fe₃O₄复合纳米粒子, 构成非均相Fenton反应体系, 催化降解水环境中的氧氟沙星抗生素。研究了CeO₂含量、H₂O₂浓度、pH等因素对CeO₂/Fe₃O₄非均相催化活性的影响, 并通过溶出铁离子测定、动力学拟合等方式对反应机理进行探究。结果表明, CeO₂/Fe₃O₄较Fe₃O₄具有更强的催化活性, 氧氟沙星的降解率随CeO₂含量、H₂O₂浓度和溶液酸度的增加而提高, 当H₂O₂浓度为100 mmol/L 以及pH为3时, CeO₂/Fe₃O₄(摩尔比=0.780)-H₂O₂体系催化降解氧氟沙星的效果最佳。CeO₂/Fe₃O₄体系催化降解氧氟沙星反应遵循一级反应动力学方程, 反应机理主要为催化剂表面的催化反应, 同时CeO₂产生氧空位的电子转移对Fe₃O₄的催化反应起到协同强化的作用。     

EPR and Magnetic Susceptibility Investigation of Fe Ions in B2O3—SrF2 Glass Matrix

The structural and magnetic properties of an oxide-fluoride mixed vitreous matrix 2B2O3-SrF2, were explored by using Fe impurities as probes.Information about the structural units involving iron ions,their valence state,the strengths and type of interactions involving them was obtained using EPR spectroscopy and magnetic susceptibility measurements.     

Acceptor related photoluminescence and field emission of ZnO:P nanostructures

ZnO:P nanobelts were self-assembly synthesized by thermal evaporation of Zn power and P₂O₅ mixture. The temperature dependence photoluminescence of ZnO:P nanostructures was studied from 81 to 291 K. As the temperature increased from 81 to 111 K, the PL intensity of DAP emission was obviously enhanced. The abnormal PL intensities were ascribed to the acceptor vibration with local phonon and lattice phonon assistant. The PL of zinc vacancy and its replica were well resolved due to the strenuous vibration of Zn vacancy. The replica of zinc vacancy emission increased while the visible emission gradually decreased with the temperature increase. It suggested that there were intensive deep acceptor vibration. The field emission properties of the ZnO:P nanostructures have been investigated according to the acceptor-related PL spectra. The influence of space charge effect on the field emission behaviors was also discussed.