Influence of heat treatment on CH4 sensing characteristics of K-, Ca-, Mg-doped SnO2 sensors

Crystallite size is closely related to CH₄ sensitivity for SnO₂ sensors. The crystallite size is growing during heat treatments such as calcinations and sintering. To develop highly sensitive methane gas sensors some dopants as crystallite growth inhibitors are added to SnO₂ powder. This paper is mainly concerned with effect of heat treatment of SnO₂ doped with various grain growth inhibitors on CH₄ sensitivity. We fabricated thick film methane gas sensors using SnO₂ powders doped with K, Ca, and Mg. There is the optimum sintering temperature and time. Sensitivity is more affected by temperature than by time. And the sensitivity is exactly the same order as crystallite size.