Аннотация:Thin films deposited by ion beam sputtering typically have a high compressive stress. This paper demonstrates that this stress can be reduced by cosputtering two materials. Thin film mixtures of zirconia (ZrO2) and silica (SiO2) were prepared with a range of compositions using ion beam sputtering. The refractive index was found to vary almost linearly with composition. The large stress observed in zirconia films was found to be reduced significantly by the addition of silica.