Abstract
Synchrotron x-ray diffraction reveals a pressure induced crystallization at about 3.4 GPa and a polymorphic transition near 10.3 GPa when compressed a liquid GaIn eutectic alloy up to ~13 GPa at room temperature in a diamond anvil cell. Upon decompression, the high pressure crystalline phase remains almost unchanged until it transforms to the liquid state at around 2.3 GPa. The ab initio molecular dynamics calculations can reproduce the low pressure crystallization and give some hints on the understanding of the transition between the liquid and the crystalline phase on the atomic level. The calculated pair correlation function g(r) shows a non-uniform contraction reflected by the different compressibility between the short (1st shell) and the intermediate (2nd to 4th shells). It is concluded that the pressure-induced liquid-crystalline phase transformation likely arises from the changes in local atomic packing of the nearest neighbors as well as electronic structures at the transition pressure.
Highlights
Phase transition in materials can be induced by varying external parameters, such as the temperature, pressure, electric or magnetic fields
Amorphous-to-amorphous transitions (AATs) induced by pressure was surprisingly observed in Lanthanide-based MGs16–20, in which the structural transition of low-to-high density polyamorphism was suggested to be driven by f electron delocalization under high pressure
We present that the GaIn alloy exhibits two transformations under compression: one is a pressure-induced liquid-to-crystalline transition at 3.4 GPa, and the other is a crystal-to-crystal polymorphic transition from monoclinic to more complex triclinic phase near 10.3 GPa
Summary
Phase transition in materials can be induced by varying external parameters, such as the temperature, pressure, electric or magnetic fields. A large number of experiments and calculations have been performed in search of pressure-induced phase transition and transition mechanism in MGs. For example, amorphous-to-amorphous transitions (AATs) induced by pressure was surprisingly observed in Lanthanide-based MGs16–20, in which the structural transition of low-to-high density polyamorphism was suggested to be driven by f electron delocalization under high pressure. Amorphous-to-amorphous transitions (AATs) induced by pressure was surprisingly observed in Lanthanide-based MGs16–20, in which the structural transition of low-to-high density polyamorphism was suggested to be driven by f electron delocalization under high pressure Another AAT was detected in main-group non-f-electron-containing Ca-Al MG. To determine whether the liquid under low pressure experiences a liquid-to-liquid transition prior to crystallization, ab initio molecular dynamics (AIMD) calculations are performed to reveal the atomic and electronic structure changes in GaIn liquid alloy under pressure
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