scholarly journals Dynamics of contact electrification

2021 ◽  
Vol 7 (22) ◽  
pp. eabg7595
Author(s):  
Mirco Kaponig ◽  
Andre Mölleken ◽  
Hermann Nienhaus ◽  
Rolf Möller
Keyword(s):  
Electrical Contact ◽  
Contact Potential Difference ◽  
Underlying Mechanism ◽  
Excess Charge ◽  
Small Sphere ◽  
Contact Potential ◽  
Contact Electrification ◽  
Scale Down ◽  
The Moment ◽  
Electrical Charging

Although the electrical charging of objects brought into contact has been observed for at least 2000 years, the details of the underlying mechanism are still not yet fully understood. The present paper deals with the very basic process of contact electrification between two metals. We have developed an experimental method to follow the charge of a small sphere bouncing on a grounded planar electrode on a time scale down to 1 μs. It reveals that the sphere is discharged in the moment of contact, which lasts about 6 to 8 μs. However, at the very moment of disruption of the electrical contact, it regains charge far beyond the expectation according to the contact potential difference. The excess charge rises with increasing contact area.

scholarly journals Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1803
Author(s):  
Zhen Zheng ◽  
Junyang An ◽  
Ruiling Gong ◽  
Yuheng Zeng ◽  
Jichun Ye ◽  
...  
Keyword(s):  
Structural Changes ◽  
Silicon Oxide ◽  
Crystalline Silicon ◽  
Contact Potential Difference ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Carrier Lifetimes ◽  
Transmission Electron ◽  
Effective Carrier

In this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlOx layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO2/AlOx interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 °C) AlOx, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 °C.

scholarly journals Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 505
Author(s):  
Krzysztof Aniołek ◽  
Bożena Łosiewicz ◽  
Julian Kubisztal ◽  
Patrycja Osak ◽  
Agnieszka Stróż ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Contact Potential Difference ◽  
Isothermal Oxidation ◽  
Potential Method ◽  
Open Circuit ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Oxide Layers

Titanium and its alloys are among the most promising biomaterials for medical applications. In this work, the isothermal oxidation of Ti-6Al-7Nb biomedical alloy towards improving its mechanical properties, corrosion resistance, and bioactivity has been developed. The oxide layers were formed at 600, 700, and 800 °C for 72 h. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), 3D profilometry, and microindentation test, were used to characterize microstructure, surface geometrical structure, and the hardness of the diphase (α + β) Ti-6Al-7Nb alloy after oxidation, respectively. In vitro corrosion resistance tests were carried out in a saline solution at 37 °C using the open-circuit potential method and potentiodynamic measurements. Electronic properties in the air were studied using the Scanning Kelvin Probe (SKP) technique. The bioactivity test was conducted by soaking the alkali- and heat-treated samples in simulated body fluid for 7 days. The presence of apatite was confirmed using SEM/EDS and Fourier Transform Infrared Spectroscopy (FTIR) studies. The thickness of oxide layers formed increased with the temperature growth from 0.25 to 5.48 µm. It was found that with increasing isothermal oxidation temperature, the surface roughness, hardness, corrosion resistance, and contact potential difference increased. The Ti-6Al-7Nb alloy after oxidation revealed the HAp-forming ability in a biological environment.

Electrical Properties of Pd-contacted Single-walled Carbon Nanotubes: A Scanning Probe Microscopy Study

2010 ◽  
Vol 1258 ◽  
Author(s):  
Oleg Kononenko ◽  
S I Bozhko ◽  
V N Matveev ◽  
V T Volkov ◽  
M A Knyazev ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Scanning Probe Microscopy ◽  
Contact Potential Difference ◽  
Single Walled Carbon Nanotubes ◽  
Scanning Probe ◽  
Contact Potential ◽  
Reliable Technique ◽  
Probe Microscopy ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

AbstractPd is widely used in producing electrodes to single-walled carbon nanotubes (SWNT). However up to now its ability to form ohmic contacts to SWNTs was not employed in scanning probe microscopy (SPM). Here we present a study of SWNTs with Pd electrodes by SPM using Pd-coated tips. SWNTs were selectively grown on oxidized silicon substrates by low pressure CVD method. Pd electrodes were prepared to SWNTs to fabricate two terminal structures for SWNTs resistance measurements. It is shown that SPM Kelvin mode is a reliable technique for SWNT detection on insulating substrate. Contact potential difference between Pd electrode and SWNT is measured using the Kelvin mode.

Determination of the local contact potential difference of PTCDA on NaCl: a comparison of techniques

2009 ◽  
Vol 20 (26) ◽  
pp. 264012 ◽  
Author(s):  
S A Burke ◽  
J M LeDue ◽  
Y Miyahara ◽  
J M Topple ◽  
S Fostner ◽  
...  
Keyword(s):  
Contact Potential Difference ◽  
Potential Difference ◽  
Contact Potential ◽  
Local Contact ◽  
Comparison Of Techniques
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