Manganese oxide–manganese tungstate composite humidity sensors

Experimental results on composites fabricated from different mole percent of MnWO4 and Mn2O3 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, Sf (R5/R98) measured at 298 K revealed that the composite MWMO-82 has the highest sensitivity, greater than 4×103. The response and recovery characteristics of MWMO-82 were assessed.