贵金属Pd离子掺杂纳米ZnSnO3的氢敏性能及掺杂机理

为了提高ZnSnO3的氢敏性能,以共沉淀法制备ZnSnO3并对其进行了贵金属Pd2＋掺杂.采用X射线衍射仪（X-ray diffraction,XRD）及透射电镜（transmission electron microscopy,TEM）对制备的气敏材料进行结构及形貌表征,并使用静态配气法测试了掺杂前后ZnSnO3的氢敏性能.结果表明：掺杂Pd2＋可显著提高ZnSnO3的氢敏性能.在工作温度为240℃、浓度为300×10-6的条件下,Pd2＋掺杂纳米ZnSnO3对氢气的灵敏度为12,是未掺杂时的3倍.基于第一性原理探讨气敏机理,计算结果表明：Pd2＋掺杂改变了ZnSnO3能带间的电子运动状态,使ZnSnO3费米能级由0.725 eV移动到1.035 eV,在费米能级附近产生新的电子峰,使其电导性能在气敏反应过程中改变更为明显.Pd2＋掺杂还使ZnSnO3表面吸附氧的能力显著增加,对提高氢敏性能起到了关键作用.     

气敏元件的技术改造—薄膜气敏元件的开发

简要叙述了气敏元件技术改造的情况,介绍了研制薄膜气敏元件的工艺流程和芯片结构以及我们已研制出的薄膜元件(SnO2,ZnO,Fe2O3,TiO2,ZnSnO3)的气敏特性和温耗特性。     

金属氧化物气敏新材料的开发

提出了开发n型金属氧化物气敏材料的理论,指出了禁带宽度Eg2 eV的材料都有可能研制薄膜气敏元件,通过Fe2O3/2%CeO2,TiO2/2%CeO2薄膜元件试制成功,论证了理论的正确性;发展了复合材料的开发理论,对ZnSnO3的气敏特性进行了测试。     

粉末溅射金属氧化物薄膜气敏元件

指出了薄膜元件能否实用化的关键在气敏层的稳定性;提出了粉末溅射和高能溅射是气敏层稳定性的保证。指出了能实用化的薄膜元件是否能生产还要有较高的成品率,这就要求对晶体管光刻工艺进行改造和发展。给出了SnO2/16%CeO2,ZnO/1%CeO2,Fe2 O3/2%CeO2,TiO2/2%CeO2,ZnSnO3（ ZnO +SnO2）元件的气敏特性。     

ZnO/ZnSnO3纳米复合物的制备及其HCHO气敏性研究

采用水热法在不同温度下制得两种氧化锌/偏锡酸锌(ZnO/ZnSnO3)复合氧化物。通过XRD、SEM、比表面积及孔隙度分析仪分别对复合氧化物的晶体结构、微观形貌、比表面积等进行表征,结果表明,160℃水热条件制得了氧化锌/片状偏锡酸锌纳米复合氧化物,而180℃条件下制得了颗粒状ZnO/ZnSnO3纳米复合物,平均粒径16nm。采用传统旁热式结构对上述两复合氧化物进行HCHO敏感性能研究,结果发现两种复合氧化物对甲醛都表现出良好的气敏特性,其中氧化锌/片状偏锡酸锌复合氧化物的甲醛气敏特性尤为突出,工作温度110℃时对0.5×10-6甲醛有很好的响应。     

掺杂ZnSnO3气敏特性及实用性研究

本文通过对ZnSnO3传感器进行各种掺杂来提高其灵敏度、选择性和工作温度.结果发现:在所有的掺杂剂中,TiO2能显著提高其灵敏度而且灵敏度是无掺杂ZnSnO3传感器的两倍多,并且最佳的掺杂量为5%mol.此外,这种掺杂ZnSnO3传感器的回复-响应时间为10S左右,足够实际应用.在有其它气体存在的情况下,这种掺杂ZnSnO3传感器仍然对乙醇具有较高的选择性.用SEM对其进行了解释.因此,掺TiO2的ZnSnO3传感器对乙醇具有较高的灵敏度并且保持较高的选择性,能够重复使用以及60h后,其灵敏度可保持稳定值.     

一种银掺杂的ZnO/ZnSnO3复合光催化剂的制备及其光催化性能

以Zn(NO3)2·6H2O和SnCl4·5H2O为原料,氨水为沉淀剂,利用沉淀一煅烧法结合光沉积法分别制备了ZnO、ZnSnO3、ZnO/ZnSnO3和Ag/ZnO/ZnSnO3单、双和3组分光催化剂.利用X射线衍射(XRD)、扫描电镜(SEM),紫外-可见漫反射光谱(UV-Vis)和X射线荧光光谱对样品进行了表征....     

Zn-Sn-O系统透明导电薄膜的制备及其性能

本文采用溶胶-凝胶(Sol-Gel)过程和旋涂技术,通过高温烧结,得到了Zn-Sn-O系统的薄膜。结合干凝胶的差示扫描热分析(TG-DSC)和薄膜的X射线衍射分析(XRD),研究了干凝胶在烧结过程中发生的反应。通过控制溶胶的组成和薄膜烧结温度,得到了较纯净的Zn2SnO4晶相薄膜和ZnSnO3晶相薄膜。ZnSnO3晶体薄膜的电阻率显著低于Zn2SnO4晶体薄膜;N2气氛热处理后,ZnSnO3薄膜的电阻率升高而Zn2SnO4薄膜的电阻率大幅降低;当[Zn]/[Zn+Sn]=50.3at%时,薄膜的晶相仍为ZnSnO3,其电阻率较[Zn]/[Zn+Sn]=50.0at%的薄膜降低,约为8.0×102Ω.cm-1。通过上述两种晶相薄膜的X射线光电子能谱分析(XPS),探讨了这两种晶体不同的导电机理:Zn2SnO4晶体通过其中的氧空位导电,而ZnSnO3晶体则以间隙阳离子导电。紫外-可见光透过率(UV-Vis)分析表明:Zn2SnO4和ZnSnO3晶体薄膜在400~900nm的可见光波段的透过率可达80%以上。     

掺杂Al2O3纳米粉对ZnO厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Al2O3纳米粉(平均粒径5 nm)为原料,利用传统的厚膜气敏传感器制备工艺制备了纯ZnO厚膜气敏传感器和掺杂Al2O3(掺杂量为2wt%和5wt%)的ZnO厚膜气敏传感器.对这三种厚膜传感器的本征电阻及对乙醇蒸汽的敏感特性进行了测试.结果表明:掺杂少量Al2O3纳米粉可明显降低ZnO气敏传感器的本征电阻,改善传感器的烧结性能,同时还可降低其最佳工作温度,提高器件对乙醇的灵敏度.结合厚膜气敏传感器的显微结构分析结果,对出现上述差异的原因进行了讨论.     

碳纳米管掺杂纳米WO3气敏材料的制备及其应用

为降低WO3气敏元件的工作电压,改善WO3基敏感材料的气敏性能,采用化学吸附沉淀-水热法合成WO3和WO3/SWCNT复合材料,并研究矿化剂用量和SWCNT掺杂量对其气敏性能的影响.结果表明,大剂量矿化剂的使用会降低WO3的气敏性能;碳纳米管掺杂可以使WO3在较低的工作温度下有较高的灵敏度.SWCNT掺杂量为1％的元件...     

Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method

The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 °C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out.     

Characterization of the MgO nano powder synthesized by using a liquid phase precursor method for plasma display panels protecting layer

The characterization of MgO nano powders that were synthesized using a conventional firing liquid phase precursor, rapid firing liquid phase precursor and rapid cooling firing liquid phase precursor were investigated as a function of the heating and cooling rates and the concentration of the impregnated Mg(NO3)2 x 6H2O solution from 1 to 20%. The relative intensity of diffraction peak in the MgO nano powder increased with increasing firing temperature from 800 to 1200 degrees C, indicating a higher crystalline MgO nano powder. In addition, the relative intensities of the MgO nano powder synthesized at the designated temperature showed similar behavior regardless of the impregnated Mg(NO3)2 x 6H2O solution concentration from the XRD analysis. The field emission scanning electron microscope and high resolution transmission electron microscope analysis showed that the size and shape of the MgO nano powder can be controlled by the temperature, the firing and cooling processes, and the impregnated Mg(NO3)2 x 6H2O solution concentration. Moreover, the CL spectra of the synthesized MgO nano powders showed a higher luminance efficiency than commercial MgO nano powder.     

Synthesis temperature dependence of morphologies and properties of cobalt oxide and silicon nanocrystals

Cobalt and cobalt oxide nanocrystals were synthesized on Si substrates from aqueous cobalt nitrate [Co(NO₃)₂·6H₂O] powder via chemical vapor deposition method. Scanning electron microscope, field emission scanning electron microscope, and transmission electron microscope observations show different morphologies, such as continuous films, nano-bars, nano-dices, and nano-strings, depending on the synthesis temperature. The crystal structure characterization was conducted using X-ray diffraction methods. Furthermore, the properties of the samples were characterized using Raman spectroscopic analysis and vibrating sample magnetometer. The morpholo- gy change was discussed in terms of synthesis environments and chemical interactions between cobalt, oxygen, and silicon.     

机械合金化制备FeSiAl合金粉末的研究

采用机械合金化的方法制备了FeSiAl合金粉末样品。以硅钢粉和铝粉为原料,按摩尔分数Fe3Si0.4Al0.6配比,研究其机械合金化过程,并对机械合金化的机制进行探讨。用激光粒度仪、X射线衍射(XRD)和扫描电子显微镜分析材料的粒度、形貌和结构。研究表明,Fe3Si0.4Al0.6混合粉末球磨30h后,粉末粒径可达18μm;Fe3Si0.4Al0.6混合粉末经高能球磨20h后,形成具有bcc结构的α固溶体;球磨继续进行,合金化的粉末和晶粒不断细化。     

在酸性条件下采用高能球磨法制备 Cu2O纳米粉末

采用行星球磨机在pH=2的稀盐酸溶液中对Cu粉进行球磨，球磨机简体和磨球材质均为纯Cu，球料比为20：1，球磨机转速为300r／min，通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）等对球磨产物进行了表征．XRD结果表明，球磨3h后，所加入的纯Cu粉末基本转化为Cu20粉末．球磨70h后得到纯的Cu20粉末，粉末粒度为50-100nm．并对Cu20纳米粉末的生成机制及球磨工艺参数对Cu20形成的影响进行了讨论．     

Synthesis of cadmium selenide nanorods by polyethylene glycol-assisted solvothermal process

Cadmium selenide nanorods were successfully synthesised using Cd(NO₃)₂ and Se powder in ethylenediamine by the polyethylene glycol-assisted solvothermal reaction at 200°C for 72?h. Phase of the product was detected using X-ray powder diffractometer and selected area electron diffractometer. The XRD and electron diffraction patterns were simulated by CaRIne Crystallography 3.1 program and were found to be in accordance with those of the interpretation. The product analysed using scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscopy, appeared as the nanorods with their growth in the [1?1?1] direction. The direct energy band gap, determined from the UV–visible absorbance, was 1.82?eV.     

Fe基非晶纳米晶喷涂粉末的制备及性能

利用氩气雾化方法制备出了Fe48Cr15Ni15Si5.8B2.7Mo6W4Al2Co非晶合金粉末,利用扫描电镜、透射电镜、X射线衍射仪、粒度分析仪和差示扫描量热仪对粉末的微观结构、相组成、粒径分布以及热稳定性进行了分析。研究表明,所制备的粉末结构为非晶纳米晶结构,纳米晶的尺寸约为20～40nm;粉末颗粒形貌呈球形或椭球形,流动性很好。差热试验表明,粉末具有很强的非晶形成能力并且热稳定性非常好;筛分出来的小于47!m目的粉末粒度正态分布比较窄。     

Synthesis and characterization of copper sulfide nanocrystal with three-dimensional flower-shape

New copper sulfide nanocrystals with three-dimensional (3D) flower-shape were synthesized by using copper acetate (Cu(ac)₂) and citric acid (cit) and thiourea (Tu) as precursors at 160 °C in an anhydrous ethanol by a solvothermal route. The structure and properties of as-prepared products were characterized by X-ray powder diffraction, transmission electron microscopy, field emission scanning electron microscope and scanning electron microscope. The optical properties of copper sulfide nanocrystals were examined by UV–vis and FTIR. The crystal growth mechanism was also proposed.     

微量Si在W－7Ni－3Fe重合金中的行为

研究了掺到原料Ｗ粉中微量Ｓｉ（４００ｐｐｍ）在Ｗ－７Ｎｉ－３Ｆｅ重合金中的分布及在液相烧结过程中的行为．结果表明，Ｓｉ主要以固溶形式分布在Ｗ晶粒中．Ｘ射线光电子能谱（ＸＰＳ）分析发现，在掺杂Ｓｉ的Ｗ－Ｗ及Ｗ－基体相界面富集ＳｉＯ２和Ｎａ２ＳｉＯ３在未掺杂试样的断口表面发现了较弱的ＷＯ２的ＸＰＳ谱，而在掺杂合金中未发现ＷＯ２．