Polymorphism and metastable phenomena in liquid tin under pressure

Polymorphism of substances under high pressures is observed and used to obtain materials with new physical properties. Here the authors present experimental results revealing phase transitions and structure of liquid tin at high pressure under metastable conditions using x-ray absorption spectroscopy and x-ray diffraction. They show that there is an abrupt change in the undercooling limit of liquid Sn above 2 GPa, where nucleation takes place into the Sn-III metastable solid phase. The liquid local structure is found to be composed of tetrahedral and close-packed configurations. The latter are found to dominate at high pressure favoring crystallization to the Sn-III metastable solid phase.