Influence of Grain Size on Gas Sensing Properties of TiO2 Nanopowders

Abstract The aim of this research is to study size – dependent effects and gas sensing properties of TiO2 nanomaterials prepared on the base of nanopowders obtained by Flame Spray Synthesis, FSS. The specific surface area (SSA) and the resulting particle sizes of the prepared powders are controlled by the flow rate of the precursor. The results concerning morphological properties of nanomaterials investigated by BET, adsorption isotherms, X – ray Diffraction, XRD, Scanning Electron Microscopy, SEM are discussed. Electrical resistivity of gas sensing tablets is measured as a function of hydrogen concentration within the range of 50 – 3000 ppm at constant temperature of 200 o C – 400 o C. Dynamic changes in the electrical resistivity upon interaction with hydrogen are large and reproducible. The sensor response increases systematically with the decrease in the temperature of operation down to 250 o C. Smaller grain size results in a higher electrical conductivity suggesting the predominant influence of intergrain contacts.