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首页> 外文学位 >Sol gel synthesis and characterization of tin oxide and doped-tin oxide nanosized materials used for gas-sensing.
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Sol gel synthesis and characterization of tin oxide and doped-tin oxide nanosized materials used for gas-sensing.

机译：用于气敏的氧化锡和掺杂的氧化锡纳米材料的溶胶凝胶合成与表征。

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摘要

SnO2-based gas sensors have been shown to be convenient tools for detecting inflammable or toxic gases diluted in air. Grain size reduction and mixed tin oxidation states are two of the main factors enhancing sensor properties of undoped and doped tin oxides.;Two tin(II) halide precursors were utilized along with variations in solvent, aging times, drying atmosphere and annealing temperatures to synthesize SnO, SnO2 or the SnO/SnO2 mixed powders by a modified sol-gel method. X-ray diffraction and UV-Visible Diffuse Reflectance Spectroscopy were the primary techniques used to characterize powder structure and properties.;It has been found that SnCl2 is a suitable precursor for synthesis of nanocrystalline mixed Sn(II)/Sn(IV) oxide powders. The ratio of SnO to SnO2 can be adjusted by sintering/annealing of the SnO/SnO 2 mixture in air. A rarely observed form of Sn3O4 and another intermediate phase, orthorhombic SnO2, can be generated at the range of 500--600°C. SnBr2 and SnBr4 can be used as precursors for an efficient low-temperature, atmospheric pressure vapor deposition of nanocrystalline SnO2, most likely via a partially hydrolyzed Sn(IV) bromide intermediate. As vapor-deposited, the average SnO 2 crystallite size is approximately 3 nm, and can be increased systematically from 3 nm to 16 nm by annealing in air.;The presence of amorphous material and the remaining hydroxyl groups in the SnO2 crystals are possible causes of the crystalline deformation of SnO/SnO2 materials precipitated from SnCl2. SnO 2 obtained from the SnO/SnO2 mixture are more disordered than that from tin(H) oxyhydroxide and from SnO2 gel heated at the same sintering temperature. The more disordered material has lower band gaps and bigger Urbach energies.;Coprecipitation of a second metal, such as Cr, Fe, Zn, Co, K and Cu, results in variations in SnO2 crystallite growth patterns, depending on identity of the added dopant.;Metal oxide materials mixed with polypyrrole were tested as composite thick film gas sensors at room temperature. The materials exhibited sensitivity and selectivity patterns depend on phase composition and morphology. The materials exhibit promise for construction of an integrated array of multiple SnO 2-based sensors to analyze organic vapor mixtures at ambient temperature.
机译：基于SnO2的气体传感器已被证明是检测空气中稀释的易燃或有毒气体的便捷工具。减小晶粒尺寸和混合锡氧化态是增强未掺杂和掺杂的氧化锡传感器性能的两个主要因素。；利用两种卤化锡（II）前体以及溶剂，老化时间，干燥气氛和退火温度的变化来合成通过改进的溶胶-凝胶法制备的SnO，SnO2或SnO / SnO2混合粉末。 X射线衍射和紫外可见漫反射光谱法是表征粉末结构和性能的主要技术。已发现SnCl2是合成纳米晶Sn（II）/ Sn（IV）混合氧化物粉末的合适前体。 。可以通过在空气中对SnO / SnO 2混合物进行烧结/退火来调节SnO与SnO2的比例。在500--600°C的温度范围内，可能会生成很少见的Sn3O4形式和另一种中间相正交晶SnO2。 SnBr2和SnBr4可以用作纳米晶SnO2的有效低温，大气压气相沉积的前体，很可能是通过部分水解的Sn（IV）溴化物中间体来进行的。进行气相沉积后，平均SnO 2晶粒尺寸约为3 nm，并且可以通过在空气中退火而从3 nm逐渐增加到16 nm。 SnCl2沉淀的SnO / SnO2材料的晶体变形的变化。由SnO / SnO2混合物获得的SnO 2比由羟基氧化锡（H）和在相同烧结温度下加热的SnO2凝胶获得的SnO 2更无序。较无序的材料具有较低的带隙和较大的Urbach能量。第二种金属（例如Cr，Fe，Zn，Co，K和Cu）的共沉淀会导致SnO2晶体生长方式的变化，具体取决于所添加的掺杂剂的种类。在室温下，将与聚吡咯混合的金属氧化物材料作为复合厚膜气体传感器进行了测试。材料表现出的灵敏度和选择性模式取决于相组成和形态。这些材料有望用于构建多个基于SnO 2的传感器的集成阵列，以分析环境温度下的有机蒸汽混合物。

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  • 作者

    Deng, Hongmei.;

  • 作者单位

    Marquette University.;

  • 授予单位 Marquette University.;
  • 学科 Chemistry Physical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 157 p.
  • 总页数 157
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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