Study of Liquid Metals under Extremely High Temperature by Using Electrostatic Levitation

The study of materials in an extremely high-temperature environment above 3000 K is still very challenging. The space and aeronautics industries, nuclear fusion plants, designs of new materials, defense industries and so on require the application of fundamental science in such extreme environments. However, high-temperature conditions cannot be easily obtained and controlled, and measurements of material properties are difficult without special tools and proper knowledge of the environment. One solution to resolve the difficulties at high temperature is to use levitation techniques because such techniques can isolate the extreme condition in space. Here, electrostatic levitation (ESL), which makes possible the study, the properties of materials at high temperature, will be introduced. ESL can be used at temperatures as high as 4000 K without contamination under high vacuum and can be used to measure phase-transition temperatures, specific heats, densities of liquids and solids, and the viscosities and surface tensions of liquids. ESL can also provide deep supercooling which cannot be obtained by using contact methods. Supercooling is important in order to achieve new materials, and an understanding of crystal formation and growth, as well as glass formation and transition. In this review, the principle of ESL, its use to measure physical properties, and its applications for nucleation and glass formation will be discussed.