O2 diffusion in amorphous SiO2 nanoparticles probed by outgassing

An experimental study of the O2 diffusionprocess in nanoparticles of amorphous SiO2 in the temperaturerange from 98 to 157 °C was carried out by Raman andphotoluminescence techniques. We studied O2 diffusion inhigh purity silica nanoparticles with a mean diameter of 14, 20,and 40 nm detecting the outgassing of molecules trappedduring the manufacturing. The kinetics of diffusion is welldescribed for all the investigated nanoparticles by the Fick’sequation proving its applicability to nanoscale systems. Thediffusion coefficient features an Arrhenius law temperaturedependence in the explored temperature range, and thediffusion coefficient values are in good agreement with extrapolation of Arrhenius law from higher temperature studies