Humidity sensitive properties of K+-doped nanocrystalline LaCo0.3Fe0.7O3

This paper reports the study of humidity sensitive properties of pure and K+-doped LaCo0.3Fe0.7O3 thick film sensors. The humidity sensitive thick films were prepared by screen printing on ceramic substrates with interdigitated electrodes. It was found that pure LaCo0.3Fe0.7O3 showed sensitivity only in the relative humidity (RH) above 54%. The addition of alkali ion K+ was beneficial for improving the humidity sensitive properties of the sample. The best results were obtained for 2 wt.% K2CO3-doped sample, which exhibited excellent linearity in the whole humidity range of 11–95%. A resistance variation of about four orders of magnitude, narrow hysteresis loop, and rapid response were obtained. The effects of dopant content on humidity sensitivity were also discussed.