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.