DECREASED ELECTROCHROMISM IN LI-INTERCALATED TI OXIDE-FILMS CONTAINING LA, CE, AND PR

Films of Ti-La oxide, Ti-Ce oxide, and Ti-Pr oxide were produced by re active de magnetron sputtering. Their composition was determined by Ru therford backscattering spectrometry. X-ray diffractometry and infrare d absorption spectroscopy indicated that the microstructure was heavil y disordered and in most cases Ti-oxidelike. Electrochemical Li interc alation/deintercalation was studied by cyclic voltammetry, and ensuing optical data were recorded by spectrophotometry. Ce addition diminish ed the electrochromism, and films with Ce/Ti atom ratios exceeding 0.3 were almost fully transparent irrespective of their lithiation, point ing at the potential applications of such films as counter electrodes in transparent electrochromic devices. The optical and electrochemical data were discussed in terms of a model based on electron insertion/e xtraction in 4f states located in the gap between the valence and cond uction bands of CeO2. (C) 1997 American Institute of Physics.