Electrical characterization of TiO2-based ceramics for VOCs

Cr doped TiO2 and TiO2/Cr2O3 powders are prepared by sol–gel technique and solid state reaction respectively. The structural and electronic properties of these powders are investigated. The responses of the materials made from the powders to benzene and formaldehyde vapors are studied. The research results show that Cr3+ can enter into the lattice as substitutional metal dopant by sol gel route at lower temperature. The segregation of Cr2O3 happens when Cr content exceed 8 at.%. The resistance of TiO2 can be remarkable decreased by doping Cr3+ as substitutional metal dopant. Besides Cr3+, the segregation of Cr2O3 also contributes to the alteration of conduction from n- to p-type. With some other catalyzer, both of Cr doped TiO2-based and Cr2O3/TiO2-based ceramics can detect benzene and formaldehyde vapors at 21 ppm.