Static electrification of solid oxide in liquid metal and electrical double layer at the interface

Area of Science:

• Electrochemistry
• Materials Science
• Surface Science

Background:

• Static electrification in solid-liquid metal systems arises from electron transfer.
• An electrical double layer forms at the interface due to excess electrons from the oxide in the liquid metal.
• This double layer comprises an immobile inner layer, a compressed diffuse layer, and a flat layer.

Purpose of the Study:

• To investigate the static electrification of solid oxides in liquid metals.
• To measure the potential of the compressed diffuse layer and the excess electron density of the flat layer.

Main Methods:

• Differential potential analysis was employed to measure the compressed diffuse layer potential.
• The induced electromotive force (emf) method was utilized to determine the excess electron density in the flat layer.

Main Results:

• Most oxides in liquid metals were found to possess positive surface charges.
• The potentials of the compressed diffuse layer ranged from 3 to 42 microvolts, indicating significant compression.
• Excess electron densities were on the order of 10^22 electrons/m^3 of mercury.
• Contributions to oxide surface charges ranged from 10^17 to 10^18 charges/m^2 for oxide/mercury systems at 0.3 wt% solid density.

Conclusions:

• The study quantifies the electrical double layer characteristics at the oxide-liquid metal interface.
• The findings highlight the compressed nature of the diffuse layer and the significant contribution of excess electrons to surface charge.
• Results provide insights into the interfacial electronic properties of semiconducting oxides in liquid metal environments.