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Li conduction in sputtered amorphous Ta2O5
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.ORCID iD: 0000-0002-8279-5163
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.ORCID iD: 0000-0002-5496-9664
2001 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, no 5, A418-A421 p.Article in journal (Refereed) Published
Abstract [en]

Electron and Li ion conducting properties of room temperature sputtered amorphous tantalum oxide (a-Ta2O5) films were studied in order to evaluate the feasibility of using a-Ta2O5 in electrochromic device applications. The films were investigated using the galvanostatic intermittent titration technique, impedance spectroscopy, and isothermal transient ionic current measurements. It was found that the a-Ta2O5 met two out of three requirements posed on a Li ion conductor in a WO3 based electrochromic device. There was a negligible intercalation in the potential window used in WO3-based electrochromic devices (above 2.4-2.5 V vs. Li/Li+). Furthermore, in this potential region, the chemical diffusion coefficient for Li was larger than the corresponding quantity in WO3. However, there was a nonzero electron conductivity in the a-Ta2O5 films, not observed in the chemical vapor deposition-made β-Ta2O5 investigated earlier. Still, the ionic conductivity was approximately one order of magnitude larger than the electronic one.

Place, publisher, year, edition, pages
2001. Vol. 148, no 5, A418-A421 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-89902DOI: 10.1149/1.1359196Scopus ID: 2-s2.0-0009639725OAI: oai:DiVA.org:uu-89902DiVA: diva2:161752
Available from: 2002-05-15 Created: 2002-05-15 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Charged Particle Transport: As Information Source about Ion Conductors, Dielectric Materials, and Drug Delivery Systems
Open this publication in new window or tab >>Charged Particle Transport: As Information Source about Ion Conductors, Dielectric Materials, and Drug Delivery Systems
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis treats charged particle transport, mostly in solid materials but also, to some extent, in aqueous media. Three major types of materials have been investigated; dielectric materials, ion conductors, and drug-delivery systems.

The frequency-dependent dielectric permittivity of sputtered amorphous thin film tantalum oxide (Ta2O5) has been determined by using impedance spectroscopy. A new interpolation formula has been derived, that interpolates between the two power-law regions at low and high frequencies usually observed in the dielectric spectrum. This formula is based on a regular-singular-point (RSP) analysis of the conduction process, and the power-laws in the dielectric spectrum are interpreted in terms of RSPs of the underlying rate equation for the corresponding polarization-current response function.

Lithium transport properties of Ta2O5 have been analyzed by using the galvanostatic intermittent titration technique and by isothermal transient ionic current measurements. Chemical and component diffusion coefficients for intercalated lithium have been extracted. Moreover, the ion conduction process has been analyzed theoretically, and expressions for transient ionic currents derived, both for single ion-conducting layers and for three-layered structures of ion conductors.

Electrical measurement techniques have also been applied to pharmaceutical systems. The alternating ionic current technique has been developed as a tool for determining the release of electrically charged drug substances in aqueous media. Tablets made of agglomerated micronized cellulose have been investigated, and sodium chloride has been used as a model drug. An attempt has been made to describe the combined drug dissolution and drug release processes in mathematical terms.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2002. 82 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 725
Keyword
Materials science, Materialvetenskap
National Category
Materials Engineering
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-2103 (URN)91-554-5347-3 (ISBN)
Public defence
2002-06-07, the Hägg Lecture Hall at the Ångström Laboratory, Uppsala, 09:30
Opponent
Available from: 2002-05-15 Created: 2002-05-15Bibliographically approved

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Frenning, GöranNiklasson, Gunnar AStrømme, Maria

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