Humidity-sensitive properties based on liquid state LiZnVO 4-doped SnO 2

Abstract

Ceramic humidity sensitive samples composed of the SnO 2–LiZnVO 4 system were synthesized in liquid state and characterized by SEM. Compared with the sample synthesized in conventional solid-state reaction, the sample synthesized in liquid state has the advantages of lower impedance in the low relatively humidity (RH) range and better impedance-RH linearity. The effect of different levels of liquid-state doping of LiZnVO 4 on the humidity-sensitive characteristics was studied. It was found that humidity-sensitive characteristics and microstructure can be improved by controlling the level of liquid-doped LiZnVO 4. The best results were obtained with the 10 mol% LiZnVO 4-doped sample, which exhibited excellent linearity in the humidity range of 11–93% RH. An impedance variation of more than four orders of magnitude, better impedance-RH linearity, high BET surface area, a narrow hysteresis loop, and rapid response were obtained. SEM micrographs of the grain structures and complex impedance analysis confirm that high performance of the sensitive layer is associated with a fine microstructure morphology, which is characterized by suitable rod shaped grains forming mesopores and by well-distributed LiZnVO 4 additives, forming a thin glassy surface covering.