Low temperature TiO2 based gas sensors for CO2

摘要: Abstract Monitoring the level of CO 2 , especially in closed spaces, is more and required technological applications, or human activities. Since most literature data reveal detection materials with high sensitivities over 300 °C, here we have concentrated on gas sensing abilities Cr doped TiO thin films front close to room temperature at atmospheric pressure. The were obtained by RF reactive sputtering. undoped contain a mixture anatase rutile phases. With increase content, crystallites size decreases, become pure for 4 at% concentration. We found out that these material based sensors are sensitive higher concentration, optimum operating approaching temperature, determining fact low energy consumption. explanation related observed oxygen vacancies number (which evidenced clarified), also presence phase, whose dielectric constant (compared anatase), its finer crystallites, determine better sensing. More, surface active area increases, as rougher contents. 3+ percentage enhance power interaction adsorbed species (O and/or ). A grain boundary model was proposed thermal activation electrical conductivity. barrier height boundary, impurities concentration (characteristic parameters this model) calculated agree well literature.