MECHANISM OF HUMIDITY SENSING OF TI-DOPED MGCR2O4 CERAMICS

The mechanism of humidity sensing of Ti-doped MgCr2O4 ceramics has bee n investigated using a combination of various techniques, such as cycl ic voltammetry, electron spin resonance spectroscopy (ESR), microcalor imetry and point of zero zeta potential measurements, to illustrate th e importance of the distribution of acidic and basic sires on the surf ace. Powder X-ray diffraction patterns prior to the measurements confi rm the single-phase behavior of MgCr2O4 as well as the expansion of th e spinel lattice with the incorporation of Ti. The evidence obtained f rom electrochemical and ESR experiments indicates the crucial role of the Cr3+/Cr2+ redox change on the surface as the main reason for humid ity sensing.