Design of high-performance sensors by using specific sensing function of hetero-junction interfaces between ionic conductor and semiconductor

本研究旨在设计、构建和控制离子导体和氧化物半导体之间的新型异质结界面，从而开发出性能显著改善的高温传感器件，赋予其特定的气敏功能。1）采用氧化物敏感电极，研制了一种稳定氧化锆（YSZ）基高温碳氢化合物选择性检测传感器。在所测试的14种氧化物中，CdO最适合作为管式传感器的敏感电极，在600 ℃下对空气中的丙烯具有选择性和快速响应。2）采用氧化物敏感电极的YSZ传感器也用于NOx的检测。在所测试的尖晶石型氧化物中，ZnFe_2O_4在550-700 ℃范围内对空气中NO_2的灵敏度最高。3）YSZ和SnO_2的组合电极在475 ℃时对空气中N_2O的灵敏度较高。在SnO_2中添加氧化物（如Bi_2O_3和Sm_2O_3）可以有效地提高N_2O的灵敏度。4）研究了在敏感电极中引入In_2O_3的NASICON基CO_2敏感器件。结果表明，在潮湿条件下，易于获得室温下的CO_2气敏性能。5）设计了一种基于NASICON的电流型NOx传感器，用于空气中总NOx的检测。为了使器件对NO_2和NO都敏感，传感Au电极上覆盖有NO氧化催化剂。在150 ℃时，该器件具有WO_3和载铂SiO_2双层催化层，其电流响应与NO_2浓度成正比，NO浓度可达1 ppm。

The present study aimed to design, construct and control new hetero-junction interfaces between ionic conductor and oxide semiconductor and then to develop high-temperature sensing devices whose properties were drastically improved by giving specific gas-sensing function. Consequently, the following results were obtained.1) By using an oxide sensing electrode, a stabilized zirconia (YSZ)-based sensor was developed for the selective detection of hydrocarbons at high temperature. Among the 14 kinds of oxide tested, CdO was found to be best suited for the sensing electrode of a tubular device, giving selective and quick response to propylene in air at 600 ℃.2) An YSZ-based sensor using oxide sensing-electrode was also examined for NOx detection. Among spinel-type oxides tested ZnFe_2O_4 has the highest sensitivity to NO_2 in air at temperatures of 550-700 ℃.3) It was found that the combination of YSZ and SnO_2 sensing electrode gave a relatively high sensitivity to N_2O in air at 475 ℃. The addition of a foreign oxide (e.g. Bi_2O_3 and Sm_2O_3) to SnO_2 was effective to improve the N_2O sensitivity.4) A NASICON based CO_2 sensing device with In_2O_3 introduced in the sensing electrode was investigated. It was shown that the CO_2 sensing capability at room temperature was easily attained under humid condition. Some sorts of auxiliary phases such as NaHCO_3 and Na_2CO_3 were suspected to form spontaneously on the NASICON disk surface to give CO_2 sensitivity.5) A NASICON based amperometric sensor was designed for the detection of total NOx in air. To make the device sensitive to both NO_2 and NO, the sensing Au electrode was covered with NO oxidation catalysts. The device attached with double catalyst layers of WO_3 and Pt-loaded SiO_2 produced current response proportional to the concentration of NO_2 or NO up to 1 ppm at 150 ℃.