Effects of Experimental Parameters on the Work Function Measurement: A Kelvin Force Microscopy Study

Kaja, Khaled; Chevalier, Nicolas; Mariolle, D.; Bertin, F.; Feuillet, G.; Chabli, Amal

doi:10.1063/1.3251225

Cited by 7 publications

(6 citation statements)

References 5 publications

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“…The Volta potential of platinum in elevated humidity has been demonstrated at room temperature to be <50 mV. 29,49,50 After the first cycle measurement, the sample was dismantled from the microscope and placed in an air-sealed container with fixed humidity of 76% RH, which was controlled using an open reservoir with saturated NaCl solution, for 20 h. 51 Then, a second measurement cycle was done. The entire measurement protocol is listed in Table II.…”

Section: Methodsmentioning

confidence: 99%

In-Situ Time-Lapse SKPFM Investigation of Sensitized AA5083 Aluminum Alloy to Understand Localized Corrosion

Liew

Örnek

Pan

et al. 2020

J. Electrochem. Soc.

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Sensitized AA5083-H2 aluminum alloy was exposed to chloride-laden thin-film electrolyte at ambient temperature (20%–85% relative humidity) and the local Volta potential measured, in-situ and in real-time, using the Scanning Kelvin Probe Force Microscopy, with the intention to elucidate the earliest stage of localized corrosion. Positive Volta potentials vs alloy matrix were measured for magnesium silicides in ambient air, which, however, underwent a severe nobility loss during corrosion, causing their nobility to invert to active potentials (negative) relative to the alloy matrix. The reason for the nobility inversion was explained by the preferential dissolution of Mg2+, which resulted in an electropositive surface. Aluminides, both with and without silicon, were seen to form the main cathodes at all exposure conditions. The local alloy matrix next to closely-separated aluminides were seen to adopt the Volta potential of the neighbor aluminides, which, hence, resulted in local corrosion protection. The phenomenon of nobility adoption introduced in this work raises questions regarding the anode-to-cathode ratio, which was observed to change during corrosion, and the resulting impact to localized micro-galvanic corrosion. This work further demonstrates that it is necessary to measure the Volta potential during corrosion to reflect the true relationship between the Volta potential and corrosion potential or breakdown potential.

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Section: Methodsmentioning

confidence: 99%

In-Situ Time-Lapse SKPFM Investigation of Sensitized AA5083 Aluminum Alloy to Understand Localized Corrosion

Liew

Örnek

Pan

et al. 2020

J. Electrochem. Soc.

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“…Therefore, on a uniform sample one would not expect any influence of the tip-sample distance on the measured surface potential. However, various groups reported a dependence of U DC on the lift-height [41,42,37], where the variations in U DC reached up to 1 V. This lift-height dependence can have many different origins. First of all there is the weighted averaging of all electrostatic contributions including the cantilever itself.…”

Section: On the Lift-height Dependence In Am-kfmmentioning

confidence: 99%

Force gradient sensitive detection in lift-mode Kelvin probe force microscopy

Ziegler

Stemmer²

2011

Nanotechnology

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We demonstrate frequency modulation Kelvin probe force microscopy operated in lift-mode under ambient conditions. Frequency modulation detection is sensitive to force gradients rather than forces as in the commonly used amplitude modulation technique. As a result there is less influence from electric fields originating from the tip's cone and cantilever, and the recorded surface potential does not suffer from the large lateral averaging observed in amplitude modulated Kelvin probe force microscopy. The frequency modulation technique further shows a reduced dependence on the lift-height and the frequency shift can be used to map the second order derivative of the tip-sample capacitance which gives high resolution material contrast of dielectric sample properties. The sequential nature of the lift-mode technique overcomes various problems of single-scan techniques, where crosstalk between the Kelvin probe and topography feedbacks often impair the correct interpretation of the recorded data in terms of quantitative electric surface potentials.

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“…The tip's nobility may be altered during exposure to humidity which has been shown to be less than 150 mV as platinum does not oxidize in ambient conditions, so adsorption of a monolayer of water, if any, is not anticipated to cause substantial changes of the work function of the tip. 26,27 The experiments were repeated several times on different regions in the microstructure, capturing dozens of IMPs, and similar results were obtained, i.e. the nobility inversion was always monitored.…”

Section: Methodsmentioning

confidence: 75%

Real-Time Corrosion Monitoring of Aluminum Alloy Using Scanning Kelvin Probe Force Microscopy

Örnek

Leygraf

Pan

2020

J. Electrochem. Soc.

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The evolution of the Volta potential of grade AA6063-T5 aluminum alloy microstructure with various intermetallic phases (IMP) during corrosion exposure to chloride-laden thin-film electrolytes at ambient temperature has been investigated, in situ and in real-time, using scanning Kelvin probe force microscopy (SKPFM), to gain insight into local corrosion processes. Trenching around micrometer-sized IMPs, de-alloying, oxidation, and the deposition of corrosion products were observed, which led to an inversion of the electrochemical nobility of the IMPs relative to the alloy matrix. Most of the IMPs showed cathodic Volta potentials (high nobility) relative to the matrix at 40%–80% relative humidity (RH), which became anodic (low nobility) when the surface was moistened with aqueous sodium chloride at elevated moisture (76%–87% RH) producing concentrations up to 5–6 M of chloride. The change of the Volta potential correlated with the onset and progress of corrosion and a nobility inversion of IMPs relative to the alloy matrix was observed. The corrosion behavior and the reasons for galvanic activities among microstructural constituents were elucidated and brought into a broader context to understanding localized corrosion.

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Effects of Experimental Parameters on the Work Function Measurement: A Kelvin Force Microscopy Study

Cited by 7 publications

References 5 publications

In-Situ Time-Lapse SKPFM Investigation of Sensitized AA5083 Aluminum Alloy to Understand Localized Corrosion

In-Situ Time-Lapse SKPFM Investigation of Sensitized AA5083 Aluminum Alloy to Understand Localized Corrosion

Force gradient sensitive detection in lift-mode Kelvin probe force microscopy

Real-Time Corrosion Monitoring of Aluminum Alloy Using Scanning Kelvin Probe Force Microscopy

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