Non-ideal lithium insertion behavior of sputtered tungsten oxide films
- Pilkington Technology Centre, Ormskirk (United Kingdom)
- Univ. of Cambridge (United Kingdom). Interdisciplinary Research Centre for Superconductivity
- Univ. of Moncton, New Brunswick (Canada). Dept. de Physique
Two sets of WO{sub 3} thin films were prepared by RF sputtering from tungsten oxide and tungsten metal targets, respectively. Lithium insertion studies were carried out in these two types of films. It has been found that the films sputtered from the metal targets showed an irreversible uptake of lithium without any coloration. The aim of the present work is to study this specific behavior of such films in comparison to those deposited from tungsten oxide targets. These films have been studied by thermogravimetry, UV-Vis spectroscopy, electron probe, ellipsometry and ATR-FTIR spectroscopy. The stoichiometry of both types of film is found to be identical. The ATR-FTIR spectra show a difference in the W-O stretching vibration pattern of the two types of films, clearly indicating structural differences in the as-deposited WO{sub 3} films. However, both types of films show the presence of little or no water in the as-deposited state. Upon the insertion of lithium it is found that the films deposited from the oxide target show the formation of `bronze` right from the very early stage of Insertion as indicated by the blue coloration. This formation is reflected in the ATR-FTIR spectra by the increasing slope of the absorption in the mid-infrared range. Contrary to this behavior, the films deposited from the metal target do not show any coloration in the initial stages of lithium insertion. The infrared spectra corresponding to this behavior show little change in the mid-infrared range. However, a widening of the W-O stretching band is observed in these spectra reflecting a structural re-organization in the films. With continued lithium insertion, however, the behavior in the two types of film becomes similar. Hence, in the initial stages of coloration the quantity of lithium participating in the electrochromic coloration of the films deposited from metal target seems to be lower than in the other type of film.
- OSTI ID:
- 197609
- Report Number(s):
- CONF-950793-; ISBN 0-8194-1890-0; TRN: IM9612%%383
- Resource Relation:
- Conference: 40. annual meeting of the Society of Photo-Optical Instrumentation Engineers, San Diego, CA (United States), 9-14 Jul 1995; Other Information: PBD: 1995; Related Information: Is Part Of Optical materials technology for energy efficiency and solar energy conversion XIV; Lampert, C.M. [ed.] [Lawrence Berkeley Lab., CA (United States). Energy and Environment Div.]; Deb, S.K. [ed.] [National Renewable Energy Lab., Golden, CO (United States)]; Grandqvist, C.G. [ed.] [Uppsala Univ. (Sweden). Dept. of Technology]; PB: 379 p.; Proceedings/SPIE, Volume 2531
- Country of Publication:
- United States
- Language:
- English
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