Porous 80 MgCr2O4-20TiO(2) ceramics were investigated as humidity sensors. The ceramics sensors were obtained by cold isostatic pressing and sintering of the fine MgCr2O4 and TiO2 powders synthesized by sol-gel methods. The effects of sintering temperature on the humidity sensitivity were studied by measuring the electrical resistance in different relative humidities (R.H.) at 27 degrees C. The results indicated that the calcining temperature obviously affected the resistance variation of the sensor in the range of 11.3-84.7%RH. The resistance variation was small at a calcining temperature of 600 degrees C for 2 h. With an increase in the calcining temperature, the resistance variation increased to a maximum of 1.49 x 10(5)% at 800 degrees C for 2 h, but decreased to 7.41 x 10(4)% and 4.07 x 10(4)% at 1000 degrees C for 2 h and 1200 degrees C for 2 h respectively. Resistance variations of 90% between 11.3%RH and 84.7%RH can be performed in 25 s and 50 s for the humidity adsorption and humidity desorption respectively. The completed response times are 55 s and 90 s for the adsorption and desorption respectively. The large sensitivity and swift response of 80MgCr(2)O(4)-20TiO(2) ceramics to humidity are suitable for humidity sensing applications.

Keywords: MgCr2O4-TiO2; sol-gel method; ceramics sensor; sintering temperature; humidity sensitivity; response time