Development of NOx and CO_2 gas sensor for on-site real-time monitoring

1.利用研制的固体电解液传感装置，对CO_2和NO_2气体进行了现场实时监测。在CO_2监测方面，能够监测24小时内教室内CO_2浓度的变化，以及由于操作油风机加热器和通风而导致的室内CO_2浓度的快速增加或减少。2.采用Li_2CO_3/MSZ的CO_2传感装置的辅助相/固体电解质的界面结构，在Li2CO3-BaCO3(或Li2CO3-CaCO3)/NASICON体系中，发现在NASICON中形成了BaZrO_3(或CaZrO_3)，其厚度和结构取决于所用碳酸盐的组成。研究表明，这些界面化合物与较低的温度传感能力有很大关系。实用传感器的设计应尽可能紧凑。在这方面，有必要设计不需要特定参考气体的非分离式固体电解质装置。幸运的是，这里开发的设备本质上适合这样的设计。用Li_2CO_3/MSZ和Li_2CO_3-CaCO_3/NASICON制作的CO2传感器可以分别制成平面型和探针型，电流型NO2传感器也是探针型。

1. On-site real-time monitoring This test was carried out for CO_2 and NO_2 by using the respective solid electrolyte type sensing devices developed. As far CO_2 monitoring, capability of monitoring variations of CO_2 concentration in a school room over 24 hours, a rapid increase or decrease of indoor CO_2 concentration due to operating oil fan heater and ventilating.2.Interface structure of auxiliaty phase/solid electrolyte For the CO_2 sensing device using Li_2CO_3/MSZ,it was proven that an interfacial compound of Li_2ZrO_3 acts as an ionic bridge and that EMF is generated through a reaction between Li_2ZrO_3 and CO_2. In the case of Li_2CO_3-BaCO_3(or Li_2CO_3-CaCO_3)/NASICON,BaZrO_3 (or CaZrO_3) was found to form inside NASICON,its thickness and structure depending on the carbonate compositions used. It was suggested that these interfacial compounds have deep relevance to the lower temperature sensing capability.Design for practical sensors Practical sensors should be as compact as possible. In this respect, it is necessary to design non-separate-type solid electrolyte devices which don't need particular reference gases. Fortunately, the devices developed here were suited to such design intrinsically. The CO_2 sensor using Li_2CO_3/MSZ and Li_2CO_3-CaCO_3/NASICON could be fabricated into a planar type and a probe type, respectively.The amperometric NO_2 sensor was also a probe type.