Electronic Properties of Metallic Oxide Films on Binary Vandium Alloys

✍ Scribed by Torsten Bachmann; Winfried Vonau

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: German
• Weight: 41 KB
• Volume: 628
• Category: Article
• ISSN: 0372-7874
• DOI: 10.1002/1521-3749(200209)628:9/10<2217::aid-zaac2217>3.0.co;2-l

✦ Synopsis

The passive films on metallic titanium and on binary vanadiumtitanium were prepared electrochemically in 5 M sulfuric acid at 298 K for a constant time of 900 s. The polarization potential was adjusted at 1.75 V vs. a saturated silver chloride electrode. Possibilities to investigate the electronic properties with photoelectrochemistry and capacitance measurements of the Mott-Schottky type were demonstrated. As a result of the investigation of the electronic properties the oxide layers were indicated as n-type semiconductors with a bandgap between 2.6 and 3.3 eV and a flatband potential of about Ϫ300 up to ϩ400 mV (vs. SCE). Because of the band gap values depending on the portion of vanadium in the alloy it has to be assumed that a modification of the crystalline structure was established. This also means an improvement of the transition of electrons from the valence to the conduction band, i.e. the semiconductor properties decreased with the amount of vanadium, whereas the electric conductivity and the doping level of the semiconductor increased. The reduction of the band gap values improved the transition of electrons from valence to conduction band. Due to the current the mass transfer increases and the corrosion rises. These results are in accordance to electrochemical investigations in [1] and also to the consideration, that in the system n-type semiconductor/redox electrolyte the electron transfer mostly proceeds via the conduction band.