氣敏傳感器的器件結(jié)構(gòu)優(yōu)化和敏感材料研究
發(fā)布時間：2018-09-18 10:58
【摘要】：采用SnO_2制備的氣敏傳感器具有生產(chǎn)成本低、結(jié)構(gòu)簡單、靈敏度高等優(yōu)點,是最早商業(yè)化和量產(chǎn)化的氣敏傳感器之一。本文以摻銻的納米SnO_2粉體為基礎,嘗試從貴金屬摻雜和結(jié)構(gòu)改進兩方面來改善SnO_2氣敏元件的氣敏性能。本文的主要研究內(nèi)容與結(jié)果如下:通過厚膜絲網(wǎng)印刷技術(shù)制備了不同電阻值的微加熱器,測量了加熱功率和溫度的關系以及相同功率下的3D熱分布圖和環(huán)境溫度對加熱器的影響,在兼顧加熱速率和熱穩(wěn)定性的前提下,調(diào)整元件基片尺寸和加熱器面積可以獲得良好的加熱效率,確保敏感材料能得到均勻穩(wěn)定的加熱。實驗結(jié)果表明,微加熱器元件升溫速率快,加熱層溫度越穩(wěn)定,有利于提高元件的穩(wěn)定性。以SnCl_4·5H_2O、SbCl_3、尿素等為原料,采用溶膠凝膠法制備了納米SnO_2氣敏粉體,通過掃描電子透鏡(SEM)、X射線衍射儀(XRD)等手段對納米SnO_2粉體進行了觀察和表征。測量結(jié)果表明,采用溶膠凝膠法制備的SnO_2粉體平均晶粒尺寸大小約為25nm,形貌為球形,銻離子進入SnO_2晶格中取代了錫離子,沒有其他雜相。在SnO_2材料中分別摻入0.1mol%、0.3mol%和0.5mol%的銻,測量了元件的氣敏性能,其中摻入0.1mol%銻的元件的性能最佳。實驗研究了Ag、Pt摻雜對元件氣敏性能的影響。實驗結(jié)果表明Ag摻雜可以有效的抑制丙酮對乙醇的干擾。發(fā)現(xiàn)Pt摻雜使元件的靈敏度有了極大的提高,有望制備成高濃度乙醇元件。運用復阻抗分析法對元件的氣敏機理進行了研究,結(jié)果表明,SnO_2氣敏傳感器的敏感作用在低濃度時主要來自于氣敏材料中的晶界作用,材料的晶界作用達到飽和,靈敏度的提升主要來自元件電極表面與敏感材料之間的相互作用。因此,改善電極材料的表面結(jié)構(gòu)以及選擇電極材料對提高元件的靈敏度有重要的作用。研究了不同氣敏材料組成的雙層厚膜結(jié)構(gòu)對元件氣敏特性的影響。發(fā)現(xiàn)雙層厚膜結(jié)構(gòu)可以改變氣敏元件的靈敏度和選擇性。這種改善與雙層膜中不同氣敏材料的上下排列順序有很大關系。盡管上層膜的性能起主要作用,但下層膜的存在改變了材料的導電通路,因而改善了膜的氣敏特性,其作用機制可能與雙層厚膜界面處由于擴散效應所形成的過渡層有關。研究了環(huán)境濕度對氣敏性能的影響,在SnO_2中氣敏摻入硝酸鑭,并通過調(diào)節(jié)元件加熱功率的方法有效降低了濕度的影響,發(fā)現(xiàn)當加熱功率為0.195W時,濕度對元件性能的影響最小。
[Abstract]:The gas sensor fabricated by SnO_2 has the advantages of low production cost, simple structure and high sensitivity. It is one of the earliest commercial and mass produced gas sensors. Based on the antimony doped nanometer SnO_2 powder, this paper attempts to improve the gas sensing performance of SnO_2 gas sensor from the aspects of noble metal doping and structure improvement. The main contents and results of this paper are as follows: microheater with different resistance values was fabricated by thick film screen printing technology. The relationship between heating power and temperature and the effects of 3D heat distribution and ambient temperature on the heater were measured. The heating rate and thermal stability were taken into account. Good heating efficiency can be obtained by adjusting element substrate size and heater area to ensure uniform and stable heating of sensitive materials. The experimental results show that the higher the heating rate is, the more stable the heating layer is, and the better the stability of the element is. Nano-sized SnO_2 gas-sensing powders were prepared by sol-gel method using SnCl_4 _ 5H _ 2O-SbCl _ 3 and urea as raw materials. The nano-sized SnO_2 powders were observed and characterized by scanning electron lens (SEM) X-ray diffractometer (XRD). The results show that the average grain size of SnO_2 powders prepared by sol-gel method is about 25 nm, and the morphology is spherical. Antimony ions have replaced tin ions in SnO_2 lattice, and there are no other heterophases. The gas sensing properties of the element were measured by doping 0.1 mol% and 0.5 mol% of antimony into the SnO_2 material respectively, and the element with 0.1 mol% antimony was the best. The effect of Ag,Pt doping on the gas sensing properties of the elements was investigated experimentally. The experimental results show that Ag doping can effectively inhibit the interference of acetone to ethanol. It was found that Pt doping greatly improved the sensitivity of the element and was expected to be used as a high concentration ethanol element. The gas sensing mechanism of the gas sensor is studied by complex impedance analysis. The results show that the sensitivity of SnO-2 gas sensor is mainly due to the grain boundary action in the gas sensing material at low concentration, and the grain boundary effect of the material reaches saturation. The enhancement of sensitivity comes mainly from the interaction between the electrode surface and the sensitive material. Therefore, improving the surface structure of electrode materials and selecting electrode materials play an important role in improving the sensitivity of the elements. The effect of the double layer thick film structure with different gas sensing materials on the gas sensing characteristics of the components was studied. It is found that the sensitivity and selectivity of the gas sensor can be changed by the double layer thick film structure. This improvement is closely related to the arrangement of different gas sensing materials in the bilayer film. Although the properties of the upper layer play an important role, the existence of the lower layer changes the conductive path of the material, thus improving the gas sensitivity of the film. The mechanism may be related to the transition layer formed by the diffusion effect at the interface of the double layer thick film. The effect of ambient humidity on gas sensing performance was studied. Lanthanum nitrate was added into SnO_2, and the effect of humidity was effectively reduced by adjusting the heating power of the element. It was found that when the heating power was 0.195 W, the effect of humidity on the performance of the element was the least.
【學位授予單位】：廣州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP212
本文編號：2247695
[Abstract]:The gas sensor fabricated by SnO_2 has the advantages of low production cost, simple structure and high sensitivity. It is one of the earliest commercial and mass produced gas sensors. Based on the antimony doped nanometer SnO_2 powder, this paper attempts to improve the gas sensing performance of SnO_2 gas sensor from the aspects of noble metal doping and structure improvement. The main contents and results of this paper are as follows: microheater with different resistance values was fabricated by thick film screen printing technology. The relationship between heating power and temperature and the effects of 3D heat distribution and ambient temperature on the heater were measured. The heating rate and thermal stability were taken into account. Good heating efficiency can be obtained by adjusting element substrate size and heater area to ensure uniform and stable heating of sensitive materials. The experimental results show that the higher the heating rate is, the more stable the heating layer is, and the better the stability of the element is. Nano-sized SnO_2 gas-sensing powders were prepared by sol-gel method using SnCl_4 _ 5H _ 2O-SbCl _ 3 and urea as raw materials. The nano-sized SnO_2 powders were observed and characterized by scanning electron lens (SEM) X-ray diffractometer (XRD). The results show that the average grain size of SnO_2 powders prepared by sol-gel method is about 25 nm, and the morphology is spherical. Antimony ions have replaced tin ions in SnO_2 lattice, and there are no other heterophases. The gas sensing properties of the element were measured by doping 0.1 mol% and 0.5 mol% of antimony into the SnO_2 material respectively, and the element with 0.1 mol% antimony was the best. The effect of Ag,Pt doping on the gas sensing properties of the elements was investigated experimentally. The experimental results show that Ag doping can effectively inhibit the interference of acetone to ethanol. It was found that Pt doping greatly improved the sensitivity of the element and was expected to be used as a high concentration ethanol element. The gas sensing mechanism of the gas sensor is studied by complex impedance analysis. The results show that the sensitivity of SnO-2 gas sensor is mainly due to the grain boundary action in the gas sensing material at low concentration, and the grain boundary effect of the material reaches saturation. The enhancement of sensitivity comes mainly from the interaction between the electrode surface and the sensitive material. Therefore, improving the surface structure of electrode materials and selecting electrode materials play an important role in improving the sensitivity of the elements. The effect of the double layer thick film structure with different gas sensing materials on the gas sensing characteristics of the components was studied. It is found that the sensitivity and selectivity of the gas sensor can be changed by the double layer thick film structure. This improvement is closely related to the arrangement of different gas sensing materials in the bilayer film. Although the properties of the upper layer play an important role, the existence of the lower layer changes the conductive path of the material, thus improving the gas sensitivity of the film. The mechanism may be related to the transition layer formed by the diffusion effect at the interface of the double layer thick film. The effect of ambient humidity on gas sensing performance was studied. Lanthanum nitrate was added into SnO_2, and the effect of humidity was effectively reduced by adjusting the heating power of the element. It was found that when the heating power was 0.195 W, the effect of humidity on the performance of the element was the least.
【學位授予單位】：廣州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP212
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