Determination of oxygen diffusion in the SnO₂/stainless steel interface of thin films by spectrophotometric measurements

Diffusion processes at high temperatures can change the transmittance and reflectance curves of multilayer coatings. These changes can significantly degrade coatings which use optical interference to obtain specific optical properties. This paper describes a study of the oxygen diffusion in SnO₂/Sst interfaces using spectrophotometric measurements. A model is developed to optically describe the diffusion process in the multilayer interfaces. The validity of this model is checked experimentally using 16 samples exposed to temperatures between 475 °C and 600 °C for different exposure times: 5, 15, 50 and 120 min. Finally, these measurements are used to estimate the effective thickness of oxide formed at the interface due to oxygen diffusion, and to calculate the corresponding effective diffusion coefficients. (paper)