Sol-gel processed TiO2-K2O-LiZnVO4 ceramic thin films as innovative humidity sensors

Active elements for humidity sensors based on TiO2-K2O-LiZnVO4 ceramic thin films have been prepared by the sol-gel technique. The films heated to 600 degrees C, whose composition is Ti:K:Li:Zn:V:O = 1:0.04:0.1:0.1:0. 1:2.42 (molar ratios), are composed of semiconductor ceramics (rutile TiO2), alkal i metal oxide (K2O) and glass (LiZnVO4). At the frequency of 40 Hz, the ele ments' impedance (Z(p)), resistance (R-p) and capacitance (C-p) vs. relativ e humidity (rh) values all show variations higher than three orders of magn itude over the humidity range tested (10-99% rh), and the curves of Log(Z(p )) similar to rh, Lop(R-p) similar to rh and Log(C-p) similar to rh all sho w excellent linearity. The outstanding advantages of the elements are the g reat stability and pollutant resistance. The results also show small hyster esis, rapid responsibility, and satisfactory repeatability. The temperature and frequency affect the humidity sensitive properties obviously. (C) 2000 Published by Elsevier Science S.A. All rights reserved.