基于In2O3纳米材料的甲醛气敏元件研究

Study on In2O3-based Formaldehyde Gas Sensors

作者: 专业:电路与系统 导师:王兢 年度:2010 学位:硕士  院校: 大连理工大学

Keywords

Indium Oxide, Formaldehyde, Gas sensor, Microemulsion, Hydrothermal synthesis

        提高传感器的响应灵敏度、选择性和稳定性是目前半导体甲醛气体传感器研究的主要内容。在研究SnO2、ZnO等传统的金属氧化物半导体材料改善上述特性的同时,人们不断研究其他材料。基于In2O3材料的气敏元件工作温度较低,其对高浓度甲醛的响应特性已有报导。本论文以提高气体传感器对低浓度甲醛的响应灵敏度以及改善传感器的选择性为目的,以In2O3为基本材料,采用不同制备方法,研制表征了多种基于In2O3的复合材料,并分别研究了它们对甲醛的气敏特性。论文分别利用共沉淀法、微乳液法和水热合成法制备In2O3纳米材料,并对材料做了TG-DTA、XRD、SEM和TEM的表征。共沉淀法制备材料方便易行,但是制备的颗粒状材料粒径较大。微乳液法制备的颗粒状材料在较低温度烧制时,其粒径最小约为7.4nm。水热合成法适合制备不同形状的In2O3材料,本文中分别制备了片状、球状和花状的In2O3材料。同时还研究了含铟新材料的制备,包括SrCd2In2Ti2O10-x和In3CrTi2O10两种新材料的制备,并做了相关表征。将制备的各种In2O3及其复合材料制作成旁热式气敏元件,在静态配气系统中对各种元件的气敏特性进行测试。气敏材料包括:不同方法制备的In2O3材料,分别掺杂Ag、Pd的In2O3材料,In2O3/CdO[摩尔比1:1)复合材料,In2O3/ZrO2/Y2O3(摩尔比1.75:9:1)复合材料,SrCd2In2Ti2O10-x, In3CrTi2O10等。测试结果表明,微乳液方法制备的粒径小的In2O3材料对甲醛的气敏性能好于粒径大的材料;In2O3/CdO(1:1)复合材料气敏元件对甲醛的气敏特性明显优于其他材料的气敏元件;球状In2O3与CdO复合材料气敏元件在干扰气体为甲醇、乙醇、甲苯和丙酮时,对甲醛的选择性很好;花状In2O3与CdO复合材料气敏元件对低浓度甲醛的响应要好于其他气敏元件,对0.05 ppm甲醛响应达到了1.45,到达了国家标准;片状In2O3与CdO复合材料气敏元件对高浓度甲醛的响应很好,对50 ppm甲醛的响应高达600;制备的含铟新材料中,SrCd2In2Ti2O10-x制备的气敏元件对甲醛的气敏性能要好于In3CrTi2O10。采用定向附着生长机理,晶粒聚集过程中的晶面匹配原则,结晶学中小的纳米颗粒定向聚集生长等理论,对不同形状的In2O3材料的制备原理进行了探讨。对各种方法制备的In2O3材料的气敏机理进行了研究,分析了粒径、比表面积、孔道、吸附以及异质结等对气敏特性的影响。
    It is important for semiconductor formaldehyde gas sensor to improve their properties of response sensitivity, selectivity and stability. While the above mentioned improvements of traditional Metal-Oxide-Semiconductor materials were researched, like SnO2, ZnO and so on, people continiously researched other materials. It has been reported that the In2O3-based gas sensor has lower operating temperature and response to high concentration of formaldehyde.The paper is mainly about the study on improving response of In2O3-based gas sensors to formaldehyde in low concentration and selectivity. The composite materials based on In2O3 were prepared and characterized by several methods. The gas sensing properties of composite materials were also researched.The paper introduced the synthesis of In2O3 using method of coprecipitation, microemulsion and hydrothermal synthesis method, respectively. The tokens including TG-DTA, XRD, SEM and TEM were also done to the prepared material. The coprecipitation method is convinent and easy to do, but the grain size of In2O3 prepared by this method is bigger. The grain size of granuliform In2O3 prepared by microemulsion is relatively smaller at the same calcining temperature, the smallest grain size is about 7.4nm. Hydrothermal synthesis method is fit for preparing different shapes of In2O3 material. In this paper, nanosheet In2O3, nanoball In2O3 and flower-like In2O3 were separately synthesized. New materials containing Indium, such as In3CrTi2O10 and SrCd2In2Ti2O10-x were also researched and synthesized.The heater-type gas sensors were prepared by using In2O3 and composite materials. The gas sensors were detected in the static state distribution system. The gas sensing materials includes:In2O3 materials prepared by several methods, In2O3 materials doped separately with Ag and Pd, In2O3/CdO composite materials, In2O3/ZrO2/Y2O3(molar rate is 1.75:9:1) composite material, SrCd2In2Ti2O10-x, In3CrTi2O10 and so on.The test results indicated that In2O3 in small grain size had better gas sensing properties to formaldehyde than big grain size. The gas sensor prepared by In2O3 doped CdO in 1:1 molar ratio showed high response to formaldehyde. The gas sensor made by nanoball In2O3 doped CdO had excellent selectivity to formaldehyde when the interference gases included methanol, alcohol, methylbenzene and acetone. The gas sensor prepared by flower-like In2O3 doped CdO had higher response to low concentration formaldehyde, and the response to 0.05 ppm formaldehyde was 1.45, the result reached the national standard. The gas sensor prepared by nanosheet In2O3 doped CdO had higher response to high concentration formaldehyde, and the response to 50 ppm formaldehyde was more than 600. The gas sensing property of SrCd2In2Ti2O10-x gas sensor was better than In3CrTi2O10 in new materials containing Indium.The research about In2O3 formation of different shapes was carried, the main reasons are fixed direction attachment mechanism, the shape matching principle in the gathering process and crystal grew in small nanoparticles therory. The gas sensing mechanism about In2O3 synthesized by various methods was also studied. Particle size, specific surface, pore canal, adsorption, heterojunction were analysized.
        

基于In_2O_3纳米材料的甲醛气敏元件研究

摘要4-5
Abstract5-6
1 绪论9-20
    1.1 研制甲醛传感器的意义9-10
    1.2 半导体甲醛传感器的研究现状10-17
    1.3 In_2O_3材料的特征与应用17-18
    1.4 In_2O_3纳米粉体材料的制备方法介绍18-19
    1.5 本论文的主要工作19-20
2 气敏元件制备及气体测试系统介绍20-26
    2.1 气敏元件的制备20-21
    2.2 气体测试系统介绍21-24
        2.2.1 动态配气系统介绍21-22
        2.2.2 静态配气系统介绍22-24
    2.3 阻温曲线测试24-26
3 颗粒状In_2O_3材料的制备、表征及气敏性能测试与分析26-42
    3.1 共沉淀法制备In_2O_3材料及其表征26-27
    3.2 共沉淀法制备材料的气敏性能测试与分析27-30
    3.3 微乳液法制备In_2O_3材料30-32
    3.4 微乳液法制备In_2O_3材料的表征32-35
        3.4.1 热重—差热分析32-33
        3.4.2 X—射线衍射表征33-34
        3.4.3 透射电镜表征34-35
    3.5 微乳液法制备材料的气敏性能测试35-38
    3.6 不同元件的气敏性能比较38-39
    3.7 气敏机理分析39-41
    3.8 本章小结41-42
4 不同形状的In_2O_3材料的制备及气敏性能的测试与分析42-62
    4.1 水热合成法介绍42
    4.2 片状In_2O_3材料的制备、表征及气敏性能测试与分析42-46
        4.2.1 片状In_2O_3材料的制备42
        4.2.2 片状In_2O_3材料的表征42-44
        4.2.3 片状In_2O_3材料制备气敏元件的气敏性能测试44-45
        4.2.4 片状In_2O_3材料制备气敏元件的气敏机理分析45-46
    4.3 球状In_2O_3材料的制备、表征及气敏性能测试与分析46-54
        4.3.1 球状In_2O_3材料的制备46
        4.3.2 球状In_2O_3材料的表征46-50
        4.3.3 球状In_2O_3材料制备气敏元件的气敏性能测试50-53
        4.3.4 球状In_2O_3材料制备气敏元件的气敏机理分析53-54
    4.4 花状In_2O_3材料的制备、表征及气敏性能测试与分析54-60
        4.4.1 花状In_2O_3材料的制备54
        4.4.2 花状In_2O_3材料的表征54-57
        4.4.3 花状In_2O_3材料与CdO材料复合制备气敏元件的气敏性能测试57-60
        4.4.4 花状In_2O_3材料制备气敏元件的气敏机理分析60
    4.5 不同形状In_2O_3材料气敏性能比较60-61
    4.6 本章小结61-62
5 含铟新材料的制备、表征及气敏性能测试与分析62-67
    5.1 SrCd_2In_2Ti_2O_(10-x)材料的制备、表征及气敏性能测试与分析62-64
        5.1.1 SrCd_2In_2Ti_2O_(10-x)材料的制备与表征62-63
        5.1.2 SrCd_2In_2Ti_2O_(10-x)材料的气敏性能测试与分析63-64
    5.2 In_3CrTi_2O_(10)的制备、表征及气敏性能测试与分析64-66
        5.2.1 In_3CrTi_2O_(10)的制备与表征64-65
        5.2.2 In_3CrTi_2O_(10)的气敏性能测试与分析65-66
    5.3 本章小结66-67
结论67-68
参考文献68-73
攻读硕士学位期间发表学术论文情况73-74
致谢74-76
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