Effect of pore size distribution on humidity sensing properties of MgO doped ZrO2-TiO2 ceramic

The MgO doped ZrO2-TiO2 composite is studied for its humidity sensing chara cteristics. Though de electrical properties show very high sensitivity to h umidity, it is not useful for practical applications because of the chargin g effect. The ac conductivity vs relative humidity characteristics of the p ellet becomes linear with an increase in sintering temperature. The post tr eatment at high temperature and high humidity is found to accelerate initia l ageing of the pellet and therefore, stabilizes the characteristics more q uickly. A physical model has been proposed to correlate initial ageing, eff ect of sintering temperature and response time with pore size distribution. Pores below 300 Angstrom radii are present in abundance near the ZrTiO4 ph ase formation temperature. These pores are responsible for higher sensitivi ty in low humidity region and linear characteristics.