γ-Fe2O3基材料的气敏性能及气固界面反应的原位漫反射红外光谱分析-材料学专业论文.docxVIP

华 华 中 科 技 大 学 硕 士 学 位 论 文 II II 可使 γ-Fe2O3 表面生成 O-，产生更多的羟基基团，并在材料表面形成具备酸性特 性的活性点-(Sn4+-O2-)-和 Br?nsted 酸位点，促进气固界面反应过程，这些过程协 同作用使 γ-Fe2O3 的气敏性能提高。 关键词：γ-Fe2O3；水热合成；微滴注；气敏性能；甲醛；乙醇；气固界面；原 位漫反射红外光谱 PAGE IV PAGE IV Abstract Electrons transfer and acquisition between materials and tested gases, which leads to resistance variation of materials, is the gas sensing mechanism of metal oxide semiconductor gas sensors. As we all know, in situ DRIFTS is an effective characterization method of surface interaction process, which is widely used in the gas-solid interaction mechanism research. Moreover, the research of gas-solid interface reaction process and adsorption on materials is significant to the study of gas sensing mechanism. In this paper, in situ DRIFTS was used to the characterization of the gas-solid interface reaction process and adsorption on γ-Fe2O3-based gas sensing materials at various working temperatures. The purpose was trying to build the relationship between the gas-solid interface reaction and gas sensing mechanism. The main research work is shown in the following. γ-Fe2O3 films were printed on Al2O3 ceramic chips by using screen printing technique. XRD and FSEM results indicated that porous γ-Fe2O3 films were consisted of nano-spherical particles. The crystalline structure of the films was cubic γ-Fe2O3. The gas-solid interaction process and surface adsorbate species of formaldehyde and ethanol on γ-Fe2O3 films were characterized by in situ DRIFTS in time. The results showed that the main surface adsorption species of ethanol gases on γ-Fe2O3 were acetate, formate and ethoxide species. Formate, dioxymethylene and molecular formaldehyde adsorbate were the main surface interaction species of formaldehyde. In the end, the gas-solid interface reaction mechanism was put forward in this chapter. High gas sensitive performance double layers γ-Fe2O3/ZnO composite films were prepared by screen printing process combined with hydrothermal treatment. Gas se