Thermal stability of $SrFeO3/Al2O3$ thin films: Transmission electron microscopy study and conductometric sensing response Available to Purchase

The $SrFeO3/Al2O3$ thin film system has been studied using transmission electron microscopy (TEM). The thin films of $SrFeO3$ were grown by pulsed laser deposition onto single crystal and sintered polycrystalline $Al2O3$ substrates at room temperature (RT) and $700°C$ and subjected to annealing for various periods of time at $700–1000°C$⁠. TEM characterization showed that the morphology of the film varied with changes of deposition temperature. Films deposited at RT featured a columnar structure and those deposited at $700°C$ showed layers with crystalline grains. The interfacial structures of the films remained unchanged below $700°C$⁠. Interfacial reactions were observed following annealing at $850°C$ for 5 h. The phase transformation at the interface was characterized for the film annealed at $1000°C$ for 5 h, for which the principal phases were identified as $SrAl2−xFexO4$ and $SrFe12−yAlyO19$⁠. Evaluation for thin film conductometric sensing applications indicated that the untreated films deposited at $700°C$ onto both single crystal and sintered $Al2O3$ substrates exhibited a $p$-type gas sensor response to oxygen at $500°C$⁠.