The changing phase of liquid metals

Most elements are metals. These elements remain metallic when they are heated through their melting point at normal pressure. Perhaps more surprisingly, two elements that are non-metallic in their solid form, silicon and germanium, also become metallic on melting. Indeed, if we consider the extremes of temperature and pressure found in many geophysical and astrophysical settings – some of which are now accessible in terrestrial laboratories – even more non-metallic elements become metallic in the fluid state. This includes fluid hydrogen, which has recently been shown to be metallic at high enough temperatures and pressures.