The influence of the powder preparation route on the sensitivity of TiO2 doped MgCr2O3 ceramic humidity sensors

MgCr2O3-20 mol% TiO2 powders were prepared by different routes (mixture of oxides, combustion reaction, amorphous citrate synthesis) and characterized by XRD, BET surface area and SEM. The compacts were prepared by uniaxial pressing with similar green density and sintered at 1400 degreesC. The sintered bodies were characterized by XRD, mercury porosimetry and SEM. The dependence of the electrical impedance on the relative humidity was measured by the IS technique. The bodies developed peculiar porous structure and, consequently, peculiar humidity-sensing characteristic. The higher humidity sensibility was shown by the body with higher open porosity and narrower pore size distribution.