Humidity‐Sensitive Characteristics of La3+‐Doped and Undoped SrSnO3

The humidity‐sensitive characteristics of La 3+ ‐doped and undoped specimens were investigated at 400°C as a function of water vapor pressures. The conductivities of the specimens increased about one order of magnitude over the entire water vapor pressure range by the partial substitution of La 3+ ions for Sr 2+ in , accompanied by an increase in the humidity sensitivity. The origin of the increased sensitivity is discussed based on both changes in the defect structure of the specimens and in the behavior of chemisorbed water on the specimens. Furthermore, a sensing mechanism of a semiconductive humidity sensor is presented.