Synthesis of Tungstate Thin Films and Their Optical Properties

A simple and new synthetic method of tungstate thin films (CaWO4, MgWO4, PbWO4, ZnWO4) was developed. The absorption and luminescence spectra of tungstate thin films synthesized on quartz substrates were measured; the optical properties were also studied. It was found that CaWO4 has Eg = 5.4 eV of a direct transition nature. Tungstate thin films were strongly luminescent when irradiated with UV-light. Excitation at around 290 nm was interpreted as a singlet–triplet transition.