ABSTRACT
Mixed oxide thin films of molybdenum and tungsten were obtained by a simple and reproducible deposition technique such as radio frequency (RF) reactive sputtering. The depositions were made from composite target of W and Mo (20:80 weight ratio) in a reactive atmosphere composed of argon and oxygen. The thin layers were characterized by Rutherford backscattering analysis and X-ray diffraction. The layers were tested by volt-amperometric technique for electrical and gas-sensing properties toward carbon monoxide, a reducing gas of great importance for environmental monitoring, between 100 and 500°C. The films were capable of sensing CO in the range necessary for this application. No effect of poisoning of the surface was recorded and recovery of the resistance was complete. A concentration of CO as low as 15 ppm produced a relative variation of the conductance about 230% with response and recovery times of about 1 minute at a working temperature of 150°C.
