Infrared spectroscopy study of electrochromic nanocrystalline tungsten oxide films made by reactive advanced gas deposition

Nanocrystalline W oxide films were produced by advanced reactive gas deposi tion. The material consisted of similar to6 nm diameter tetragonal crystall ites, as found from x-ray diffraction and electron microscopy. Optoelectroc hemical measurements demonstrated electrochromism upon Li+ intercalation/de intercalation, and infrared absorption spectroscopy gave clear evidence for longitudinal and transversal optical modes being modified following the li thiation. Our data were consistent with ionic transport predominantly in di sordered grain boundaries and intercrystalline regions and with electrochro mism being associated with small polaron formation. (C) 2001 American Insti tute of Physics.