Papers by Keyword: Gas Sensitive

Abstract: The relevance of sensor response to NO₂ with the nanostructure of the sensing body was investigated for thick-film devices using ZnO(WO₃) nanocomposites. When the nanocomposites was prepared from constituent oxides by milling in a high energy ball mill for various spans of time (1–21 h), the sensor response to 100 ppm NO₂, defined as the ratio of the electrical resistance in air to that in the sample gas, was found to reach a maximum as large as about 80 at 21 h of high energy ball-milling (HEBM). XRD and SEM observations of the granular state and pore size distribution analyses indicated that increasing HEBM time gave rise especially to an increase in the volume of pores in the pore size range of 20–35 nm. It is suggested that such a change in nanostructure is responsible for the marked promotion of the response to NO₂. For comparison, the response to NO₂ of ZnO or WO₃ nanoparticles prepared by an HEBM method was also presented. In this case, the response to NO₂ can be 10 times larger at HEBM for 21 h.

Abstract: In this paper we report on the characteristics of Pd/GaN and Pd/Si Schottky barriers exposed to different gases at various temperature range from 25°C to 500°C. The characteristics of Pd/GaN and Pd/Si Schottky barriers as gas sensors were measured as a function of temperature and ambient. Both types of sensor show changes in forward current upon introduction of different gases (N2, air, H2) into the ambient. The devices can be operated at large forward current, leading to large signal size for current at short response time for switching from one gas ambient to another such as N2 to H2 (2%) in N2. The signal size increases with the increase in measurement temperature due to more efficient cracking of the gas molecules. Both types of devices appear well suited to combustion control and leak detection.