电弧等离子体制备纳米Ce—NiO的气敏特性

用Ｈ２＋Ａｒ电弧等离子体法制备纳米Ｃｅ－ＮｉＯ并研究其气敏特性。实验结果表明，与通常用作氧敏感器Ｐ型ＮｉＯ半导体材料相比，Ｈ２＋Ａｒ电弧等离子体法制备的纳米Ｃｅ－ＮｉＯ气敏材料表现出一定的ｎ型导电性，对乙炔具有很好的选择性和较同的灵敏度，其气敏特性与纳米Ｃｅ－ＮｉＯ晶粒的显微结构有关。     

电弧等离子体制备纳米ZnO的气敏特性

用Ｈ２＋Ａｒ电弧等离子体法制成纳米ＺｎＯ，ＺｎＯ－Ｆｅ，研究了其气敏特征及机理，结果表明：与其它制备方法相比，该方法制成的纳米ＺｎＯ气敏元件在没有贵金属掺杂的情况具有较高的灵敏度，工作温度为２００℃￣２５０℃，为常规元件的一半，纳米ＺｎＯ－Ｆｅ－Ｐｄ对液化石油气（ＬＰＧ）的选择性比纳米ＺｎＯ好，具有快速响应（〈１５ｓ）的恢复特性，能稳定地连续工作７０ｈ以上，可制作低功耗ＬＰＧ气敏元件。     

电弧等离子体法制备的纳米a—Fe2O3的气敏特性

用电弧等离子体法制备纳米ａ－Ｆｅ２Ｏ３并研究其气敏特性，结果表明，在没有掺杂的情况下，纳米ａ－Ｆｅ２Ｏ３就具有较好的气敏特性。其原因是纳米粒子具有较大的比表面积和较高的晶界比例，从而导致对气体的吸附能力的扩散能力增强。本文用原位ＸＲＤ方法研究了纳米ａ－Ｆｅ２Ｏ３的气敏机理，结果表明，在还原性气氛和加热条件下ａ－Ｆｅ２Ｏ３并没有被还原成Ｆｅ２Ｏ３其气敏机理主要是表面效应控制型。     

电弧等离子体法制备的纳米α－Fe_2O_3的气敏特性

用电弧等离子体法制各纳米α－Ｆｅ＿２Ｏ＿３并研究其气敏特性，结果表明，在没有掺杂的情况下，纳米α－Ｆｅ＿２Ｏ＿３就具有较好的气敏特性。其原因是纳米粒子具有较大的比表面积和较高的晶界比例，从而导致对气体的吸附能力和扩散能力增强。本文用原位ＸＲＤ方法研究了纳米α－Ｆｅ＿２Ｏ＿３的气敏机理，结果表明，在还原性气氛和加热条件下，α－Ｆｅ＿２Ｏ＿３并没有被还原成Ｆｅ＿３Ｏ＿４，其气敏机理主要是表面效应控制型。     

多功能NiO—SnO2气敏材料的敏感特性

采用化学共淀淀法合成了不同配比的ＮｉＯ－ＳｎＯ２气敏材料，用Ｘ射线衍射法分析材料的结构与组成，测试了元件的气敏性能，并利用表面催化作用较好的解释了材料的敏感机理，通过改变ＮｉＯ的掺杂量及气敏元件的加热功率，ＮｉＯ－ＳｎＯ２材料可分别实现对Ｈ２，Ｃ２Ｈ５ＯＨ的选择性检测以及对Ｃ２Ｈ５ＯＨ、Ｈ２、ＣＯ、Ｃ４Ｈ１０和汽油等气体的广谱检测。     

新型氧敏CeO2—x薄膜的制备及结构研究

用射频磁控溅射法制备了ＣｅＯ２－ｘ高温氧敏薄膜。通过改变Ｏ２／Ａｒ比，制备出不同组分和结构的ＣｅＯ２－ｘ薄膜。用Ｃｅ３ｄ的ＸＰＳ谱了Ｃｅ２＋的浓度。ＸＲＤ和ＡＦＭ分析表明，薄膜经空气中高温退火后，形成了立方体ＣａＦ２型小晶粒，晶粒大小明显依赖于退火条件和膜厚。     

高稳定性的r—Fe2O3的合成及其气敏性能研究

本文采用空气氧化Ｆｅ（ＣＯ３）ｘ（ＯＨ）２（１－ｘ）悬浮液体系，控制体系的ｐＨ和掺入适量的钇元素，合成出纳米级黄ｒ－ＦｅＯＯＨ微晶。由ＤＴＡ－ＴＧ和ＸＲＤ分析得出，由ｒ－ＦｅＯＯＨ直接脱水得到的ｒ－Ｆｅ２Ｏ３样品，具有很好的热稳定性，其ｒ－ａ相变温度可达７２５℃，且粒径为纳米级，并具有很好的气敏灵敏度和选择性。６００℃烧结的气敏元件，对液化石油气（ＬＰＧ）的灵敏度Ｓ大于７０；而在７００℃下烧结的元     

掺锡对α—Fe2O3薄膜微结构和气敏特性的影响研究

本文用常压化学气相淀积法（ＡＰＣＶＤ）制备了α－Ｆｅ２Ｏ３薄膜，对所制备的薄膜进行了Ｘ射线衍射分析和表面形貌（ＳＥＭ）分析。对薄膜的气敏特性进行了测量。结果表明，用ＡＰＣＶＤ工艺制备的α－Ｆｅ２Ｏ３薄膜对烟者极为敏感并且具有良好的选择性；本研究还对所制备的α－Ｆｅ２Ｏ３薄膜进行了有效的掺杂，对掺杂样品的气敏特性测试表明四价金属元素Ｓｎ的掺入对α－Ｆｅ２Ｏ３薄膜的气敏特性有显著的影响。实验表明用ＡＰ     

退火对氧敏CeO2—x薄膜结构及电子组态的影响

用射频磁控溅射法制备了ＣｅＯ２－ｘ高温氧敏薄膜，用Ｃｅ３ｄ的ＸＰＳ谱计算了Ｃｅ＾３＋浓度，研究了退火条件对氧敏ＣｅＯ２－ｘ薄膜的晶体结构及电子组态的影响，ＸＲＤ和ＡＦＭ分析表明，薄膜经９７３Ｋ至１３７３退火后，形成了ＣａＦ２型结构的ＣｅＯ２－ｘ其晶粒大小明显依赖于退火条件和膜厚，退火温度在９７３Ｋ至１１７３Ｋ时（２００）晶面是择优取向的，在１３７３退化４ｈ后，可得到热力学稳定的ＣｅＯ２－ｘ在退火前     

“活性等离子体—金属”反应法制备Ni—TiN复合超微粒子的研究

研究了用“活性等离子体－－金属”反应法，在Ｈ２－Ｎ２－Ａｒ混合气氛中，用直流电弧等离子体熔化Ｎｉ－Ｔｉ系二元合金，使之蒸发，凝聚成Ｎｉ－Ｔｉ复合超微粒子的方法，以及Ｎｉ－ＴｉＮ复合超微粒子的复合状态，结构，化学组成，尺寸等。     

SnO2/NiO复合半导体纳米纤维的制备及气敏性能研究

采用静电纺丝技术结合化学沉淀法和高温煅烧处理, 制备了具有不同Sn含量的SnO₂/NiO复合半导体纳米纤维。采用扫描电子显微镜(SEM), X射线衍射仪(XRD)和能量色散X射线光谱仪(EDS)对样品的形貌, 结构以及各元素含量进行表征。以乙醇为目标气体, 探究SnO₂/NiO纳米纤维的气体传感性质, 以及Sn含量对复合纳米纤维气敏性能的影响。研究结果表明, SnO₂/NiO复合纳米纤维具有三维网状结构, SnO₂复合对NiO纳米纤维的气敏性能具有明显的增强作用。随着SnO₂含量的增加, 复合纤维对乙醇气体的响应灵敏度增强, 其中响应最高的复合纳米纤维在最佳工作温度160 ℃条件下对体积分数为100×10^-6乙醇气体的响应灵敏度为13.4, 是NiO纳米纤维最大响应灵敏度的8.38倍。与市面常见的乙醇气体传感器MQ-3相比, SnO₂/NiO复合纳米纤维的最佳工作温度更低, 响应灵敏度更高, 具有一定的实际应用价值。     

使用纳米材料添加剂的新型钡钨阴极的发射性能研究

根据纳米材料特有的性质，主要研究了使用纳米材料添加剂Al2O3、NiO阴极的发射性能，结果表明使用纳米材料添加剂NiO的阴级在较低的烧结温度时，有较好的发射性能。而添加wt25Ir＋nano-NiO（uncoated）和nano-Al2O3（umoated）的阴极发射效果不好。     

网状纤维结构氧化镍的制备及其气敏性能

p型半导体金属氧化物作为气敏材料具备响应快速、选择性高的特点,用于气体传感器的制备与开发。静电纺丝法可制备具有丰富气体吸附位点的网状结构材料,增强材料的气体敏感特性。以聚乙烯吡咯烷酮(PVP)、四水合乙酸镍为原料,采用静电纺丝法制备具有网状纤维结构的p型半导体氧化镍。通过X射线衍射、扫描电镜、X射线光电子能谱和比表面积测试等分析技术对材料的结构、形貌、组成和比表面等性能进行表征,并对其气敏性能进行测定,考察煅烧温度对材料气敏性能的影响。结果表明:煅烧温度为500℃时获得的氧化镍组装成气体传感器,在工作温度为250℃时,该元件对50mg/L丙酮气体表现出快速响应特性(响应时间为5s)、良好选择性和稳定性。     

Deposition of nickel oxide by direct current reactive sputtering: Effect of oxygen partial pressure

Nickel oxide thin films were deposited by Direct Current magnetron reactive sputtering from Ni target onto SnO₂:F conductive glass substrates. The process was carried out without intentional heating, in an argon/oxygen gas mixture with various oxygen contents and discharge currents. The polycrystalline NiO thin films were deposited with controlled growth of the structure along [111] and [200] crystallographic directions for chosen conditions. Morphology of as-deposited films was found to depend on the preferentially oriented NiO crystals. Moreover, on the basis of discharge voltage as a function of the O₂ partial pressure for a constant discharge current, we present here the method to estimate the deposition conditions allowing us to achieve the desired preferential growth of transparent p-type semiconductor NiO, by Direct Current magnetron reactive sputtering.     

溶液雾化焙烧法制备氧化亚镍超细粉体

为研究雾化焙烧法制备氧化亚镍超细粉体过程原理与工艺控制,以六水合氯化镍配制水溶液,以压缩空气为载气,利用双通道内混合气流式喷嘴雾化前驱体溶液,获得微细雾滴直接在竖立管式高温电阻炉内焙烧,制备得到超细氧化亚镍粉体.采用热重-差热分析(TGA-DTA)对NiCl2·6H2O在空气气氛中的热行为进行研究,利用X射线衍射分析(...     

Gas Sensors Based on Nano/Microstructured Organic Field‐Effect Transistors

Benefiting from the advantages of organic field‐effect transistors (OFETs), including synthetic versatility of organic molecular design and environmental sensitivity, gas sensors based on OFETs have drawn much attention in recent years. Potential applications focus on the detection of specific gas species such as explosive, toxic gases, or volatile organic compounds (VOCs) that play vital roles in environmental monitoring, industrial manufacturing, smart health care, food security, and national defense. To achieve high sensitivity, selectivity, and ambient stability with rapid response and recovery speed, the regulation and adjustment of the nano/microstructure of the organic semiconductor (OSC) layer has proven to be an effective strategy. Here, the progress of OFET gas sensors with nano/microstructure is selectively presented. Devices based on OSC films one dimensional (1D) single crystal nanowires, nanorods, and nanofibers are introduced. Then, devices based on two dimensional (2D) and ultrathin OSC films, fabricated by methods such as thermal evaporation, dip‐coating, spin‐coating, and solution‐shearing methods are presented, followed by an introduction of porous OFET sensors. Additionally, the applications of nanostructured receptors in OFET sensors are given. Finally, an outlook in view of the current research state is presented and eight further challenges for gas sensors based on OFETs are suggested.     

Synthesis of NiO nanofibers and their gas sensing properties

NiO nanofibers were synthesized by an electrospinning method with polyvinyl alcohol and nickel acetate tetrahydrate as precursor materials. Individual nanofibers consisted of nanograins. A gas sensor has been fabricated using these nanofibers. Its sensing properties to NO2 and benzene were investigated. The sensor exhibited good sensitivity and dynamic properties for the tested gases. All these results suggest that the electrospinning-synthesized NiO nanofibers hold promise for realizing sensitive and reliable gas sensors.     

Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry

Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.     

氢电弧等离子体法制备的纳米镍铈粒子的催化特性

利用氢电弧等离子法制备具有储氢特性纳米镍铈粒子，并在气相苯加氢反应中研究了其催化特性，发现其催化活性与储氢特性及表面层中ＮｉＣｅ合金存在有关，且具有高的选择性和热稳定性，这与纳米粒子独特的结构及铈的加入有关。     

Preparation of nanocrystalline nickel oxide thin films by sol–gel process for hydrogen sensor applications

Preparation of nanocrystalline NiO thin films by sol–gel method and their hydrogen (H₂) sensing properties were investigated. The thin films of NiO were successfully deposited on the glass and SiO₂/Si substrate by a sol–gel coating method. The films were characterized for crystallinity, electrical properties, surface topography and optical properties as a function of calcination temperature and substrate material. It was found that the films produced by this method were polycrystalline and phase pure NiO. The H₂ gas sensitivity of these films was studied as a function of H₂ concentration and calcination temperature. The results indicated that the sol–gel derived NiO films could be used for the fabrication of H₂ gas sensors to monitor low concentration of H₂ in air quantitatively at low temperature range (< 200 °C).