Optically transparent film of BaTiO3 - TiO2 and Fe3O4 - TiO2 on acrylic substrate with water vapor treatment

Surveillance drones face the threat of detection by defensive radar system, especially for its payload housed in a transparent acrylic dome. In this work, an optically transparentfilm stack in the visible and infra-red regime which consists of BaTiO3 - TiO2 and Fe3O4 - TiO2 was successfully deposited on acrylic substrates. A seed layer of TiO2 (14 nm) was first deposited by atomic layer deposition (ALD) followed by dip coating of absorbent layers of TiO2 and BaTiO3/Fe3O4. These as-prepared oxide layer stacks were found to compromise the transmittance of the acrylic in the visible spectrum. However, when exposed to water vapour treatment for 2 mins, the TiO2 film experienced a significant surface morphology and phase transformation, causing the film to be optically transparent. The scanning electron microscopy (SEM) and energy -dispersive X- ray spectroscopy (EDX) imaging confirmed that the BaTiO3 and Fe3O4 coat remained on the acrylic substrate. Further testing was done using an ultraviolet-visible spectroscopy and a 20 to 30% and 10 to 15% improvement in the transmittance was observed for the Fe3O4 and BaTiO3 film respectively attributed to reduction in absorbance and reflection of the visible spectrum. The stacked oxide absorbent layers also demonstrated a significant reduction in the reflectance of microwave signals based on arc reflectivity measurements. (C) 2017 The Authors. Published by Elsevier Ltd.