For liquid metals, people may immediately think of mercury; in fact there are several other metals with melting point close to room temperature in addition to Mercury (Hg, MP=−38.8 °C, e.g. Caesium(Cs, MP=28.5 °C, Rubidium (Rb, MP=39 °C, Francium (Fr, estimated MP= at 27 °C), and Gallium (Ga, MP=30 °C). However, due to the issues of radioactivity, vapor pressure, and toxicity, etc, the practical liquid metal is typically Ga based eutectic alloy with melting point less than that of Ga.
The liquid metals have many normal applications:
- Thermal interfacial materials
- Flexible/stretchable electronics
- Internet of Things (IoT) devices
- Liquid metal coated fabrics; the Ga oxides can enhance the adhesion between the liquid metal/fiber
- 3D printing for electrical contacts
Typical Ga based eutectic alloys are Galinstan, with the composition of about 68% Ga, 22% In and 10% Sn , and EGaIn, with the composition of 75 wt% Ga, 25 wt% In. The property comparison among Galinstan, EGaIn, and Mercury is shown below.
