Year

2017

Degree Name

Master of Philosophy

Department

Institute for Superconducting and Electronic Materials

Abstract

Room temperature liquid metals have been widely studied because of their unique properties including large liquid range and excellent electrical conductivity. Recently, liquid metal gallium and its alloys have attracted huge interest, owing to the discovery of new phenomena based on them.

Inspired by these new phenomena, my master thesis focused on the electrochemical properties of liquid gallium and three related topics are presented as follows.

Spreading effects of liquid metal gallium have been demonstrated above the melting point of gallium. It was found that spreading of liquid metal can occur in alkaline and acid solution under an applied voltage and liquid metal can be transformed into its spherical shape when the external power supply is cut off. However, the deformations do not show up in pH neutral solution. The volumes of the liquid metal droplet, the externally applied voltage and the concentrations of the electrolyte have great influences in the spreading speed of liquid metal and the maximum top-view spreading area.

Spreading effects of liquid metal gallium in the supercooling state have been studied. The experiments were carried out in 0.5 mol/L NaOH and HCl solutions. The spreading and crystallization of liquid metal occurred simultaneously when an external voltage is applied. The crystallization rate is lower than the spreading rate at 22 °C. Our findings open new avenues for controlled liquid-solid shape reconfigurations and are of significant importance for potential applications of soft robotics and electronics.

A phenomenological study of the gallium beating heart system in both one wire electrode and one graphite ring electrode electrochemical cell configuration stimulated with a DC voltage is presented. The gallium drop is electrically connected to the graphite ring and acts as the working electrode. When a DC voltage is applied, the liquid metal droplet was jumping on the horizontal direction in the middle of graphite ring. The range of beating frequency from 2.3 to 6.1 Hz can be acquired in our experiments. As the voltage increases, the amplitudes of the oscillation of the liquid gallium droplets show dissimilar behaviors with different volumes of liquid gallium droplet.

This thesis is unavailable until Wednesday, April 04, 2018

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