Manganese oxide–manganese tungstate composite humidity sensors

Experimental results on composites fabricated from different mole percent of MnWO 4 and Mn 2O 3 for humidity sensing are described. Sintered polycrystalline disks of the composites were subjected to d.c. electrical conductivity measurements over the temperature range of 373–573 K in inert atmosphere from which the activation energies were determined. The terminal phases and the composites were subjected to d.c. resistance measurements as a function of relative humidity in the range of 5–98% RH, achieved by various water buffers at 298 K. The sensitivity factor, S f ( R 5/ R 98) measured at 298 K revealed that the composite MWMO-82 has the highest sensitivity, greater than 4×10 3. The response and recovery characteristics of MWMO-82 were assessed.