Further XRD characterization of electrochromic nickel oxide thin films prepared by anodic deposition

Electrochromic (EC) behaviour of nickel oxide (NiOx) thin films, formed by potentiostatic electrodeposition in a nickel ammine complex solution (Ni(NH3)(x)(2+);pH 9), were investigated using alkaline electrolyte solutions, KOH and (CH3)(4)NOH (pH 12.9). In both electrolytes, the fully oxidized composite films (F0.7/1.1), prepared by electrolysis at 1.1V (vs. Ag/AgCl) followed by electrolysis at 0.7 V, commonly showed broadened UV-VIS spectra in the visible and near IR region compared with that prepared at 1.1V (F1.1). Characterization of as prepared, oxidized and reduced films in the electrolytes by low angle fixed X-ray diffraction (LAXRD) was performed to explain in detail the mechanism of the EC transformation of the films based on the conversion between two types of layered structure, cl-Ni(OH),ly,2NiO(2). NiOOH or B-Ni(OH)(2)/B-NiOOH. A model according to the extraction/insertion of cations or water molecules from/into the interlayer was proposed. (C) 2000 EIsevier Science B.V. All rights reserved.