| Autor: |
Hans-Henning Strehblow, Petra Keller |
| Rok vydání: |
2005 |
| Předmět: |
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| Zdroj: |
Zeitschrift für Physikalische Chemie. 219:1481-1488 |
| ISSN: |
0942-9352 |
| DOI: |
10.1524/zpch.2005.219.11.1481 |
| Popis: |
Passive layers on tin, CuSn4 and CuSnl9 were prepared in 0.1 N KOH (pH 12.5) under potentiostatic control with systematic variation of the relevant parameters, such as potential and time, and examined by X-ray photoelectron spectroscopy. XPS studies of potentiostatically polarised Sn-electrodes show the linear growth of the oxide layer thickness with increasing potential. Angular resolved-XPS measurements and XPS-depth-profiles allow the development of a model of the passive layer: In the passive potential range it consists mainly of SnO 2 with a small contribution of SnO. Tin hydroxide was found only on top of the layer. Sputter profiles indicate a dominating SnO 2 part which increases with the potential and the passivating time. SnO was detected underneath a layer of SnO 2 with a thickness constant with potential. The passive behaviour of CuSn4 and CuSnl9 alloys is significantly different: CuSn4 behaves almost like pure Cu: In the passive range copper oxides are the passivating components with the well known duplex structure Cu 2 O/CuD,Cu(OH) 2 . Only a small amount of tin oxide is present within the layer. On CuSnl9 the formation of passive layers starts at E = -0.3 V(SHE) similar to the situation for pure tin and increases with the potential. The outer part of the passive film consists of copper oxide. Tin oxides are accumulated in the inner part of the film up to 75 atomic percent with an analogue sequence of SnO 2 on the top of SnO. Time-dependent studies for 2s to 90 min at E = 0.5 V(SHE) demonstrate reaction sequence of both elements. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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