Surface coating of small SiO2 particles with a WO3 thin film by barrel-sputtering method

Surface coating of small SiO2 flakes with a WO3 thin film was carried out by using a hexagonal-barrel-sputtering method. In order to find suitable sputtering conditions using this method, the WO3 film was coated on the glass plate by reactive sputtering under desired total pressures, oxygen fractions, and substrate temperatures. By the analysis of XRD patterns, the suitable conditions prepared for the WO3 film were determined to be a total pressure of 0.6 Pa, an oxygen fraction of 35% and 648 K. Surface coating of SiO2 particles by WO3 film was carried out under the conditions. It was found from SEM and EDS measurements that the surface of SiO2 particles was coated with a thin uniform WO3 film.