Thermal Behavior of Nanostructured Powder

Diffusion structural analysis (DSA), based on the measurement of the release of radon previously incorporated into the samples, was used to characterize thermal behavior of N-doped titania powder prepared by heat treatment of anatase in gaseous ammonia at 575°C and the reference TiO2 powder prepared from the ST-01 anatase titania powder (Ishihara Ltd., Japan). The results of DSA, surface area and porosity measurements by nitrogen adsorption, SEM micrographs, XPS, and XRD are presented and discussed. The results of DSA are in agreement with the results of other methods and indicated the annealing of the subsurface structure irregularities of the samples. Transport properties of the samples were determined from the mobility of radon atoms released on sample heating in air. The decrease of radon permeability in the porous titania powders in the temperature range 850–1000°C due to annealing of the subsurface structure irregularities, that served as radon diffusion paths in the samples, was evaluated from the DSA results.