Analysis of hydrogen fluoride with SnO2 gas sensors

The study of the sensitivty of semiconductor tin dioxide sensors towards hydrogen flouride in air and noble gases has been carried out. The signal of sensor was found to be of the donor type and essential (relative condutivity change was Δτ/τ0-0.1 for Chf=8 ppm in air). Addition of catalytic compounds, such as Al2O3 and Fe2O3, enhanced sensor's sensitivity as much as ten times. The effect seems to be caused by acid-base interaction of hydrogen fluoride with base Brønsted centres on the surface of SnO2. The addition of base centres (Al2O3, Fe2O3) enhances the sensor's signal drastically.