Pre-existence of HxWO3 in e-beam deposited WO3 films

Structural and optical properties of e-beam deposited tungsten trioxide (WO₃) films in as-deposited and electrochemically coloured states were investigated by spectrophotometric and XRD techniques. These investigations have shown the as-deposited WO₃ films to be porous and with small amount of H_xWO₃ pre-existing in them. The films further facilitate insertion of H⁺ ions on colouration resulting in tetragonal H_xWO₃ with a = 4.74Å and c = 3.19Å.