Electrochemical Fabrication of Luminescent CaWO4 and CaWO4 : Pb Films on W Substrates with Anodic Potential Pulses

Abstract

Luminescent polycrystalline films of and have been prepared on tungsten substrates by applying low anodic potential pulses at tungsten electrodes in alkaline solutions containing calcium ion or calcium and lead ions. Anodically grown films show weak luminescence and broad X‐ray diffraction peaks. The luminescence band of the film is shifted toward a longer wavelength (red shift) compared with that of the powder prepared by a conventional solid‐state method. By postannealing the anodically grown CaWO4 film at high temperatures, luminescence intensities are enhanced, and the luminescence band maximum has been blue shifted to 420 nm. films doped with a trace amount of ion, electrochemically prepared in alkaline solutions containing calcium and lead ions, show a decrease in the intensity of luminescence maybe because of hydroxides or of hydrated water. By postannealing, the intensity of luminescence is enhanced dramatically, and the luminescence band maximum is red shifted to 444 nm in comparison to that of undoped films. © 1999 The Electrochemical Society. All rights reserved.