Humidity sensitive characteristics of Zn2SnO4-LiZnVO4 thick films prepared by the sol-gel method

Thick film ceramic humidity sensitive layers composed of the Zn2SnO4-LiZnVO4 system were sintered using nanometer powders. The humidity sensitive powders prepared by the sol-gel route have the advantages of lower resistance in the low relative humidity (RH) range, better resistance-RH linearity and long-term stability compared with layers sintered from conventional solid state reaction powders. The impedance measurements at different operation frequencies indicate that the sensors sintered at 900 degreesC for 1 h have an optimum resistance-RH linearity at 1 kHz. scanning electron microscopy (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 LiZnVO4 additives, forming a thin glassy surface covering. (C) 2002 Published by Elsevier Science B.V.