physica status solidi (b) · 2011 · 14 citations · 15 references
Natural SciencesMaterials SciencePhysicsCondensed Matter PhysicsCrystal StructureNanomaterialsHigh-pressure ThermodynamicsPhase ChangePhase TransitionsSolid-state Phase TransitionsX-ray CrystallographyX-ray DiffractionHigh-pressure Phase BehaviorHigh-pressure Phase StabilityHigh-pressure Phase TransitionsNanoscale Phase TransitionsPhase Transitions In NanomaterialsPressure-induced Phase TransitionsPressure-temperature Phase BehaviorSurface Energy Effects
Abstract The structural transition of CaF 2 nanocrystals was studied by in situ high pressure synchrotron radiation X‐ray diffraction measurements up to about 46.5 GPa at ambient temperature. A pressure‐induced fluorite structure ( Fm3m ) to orthorhombic PbCl 2 ‐type structure ( Pnma ) transition starts at 14.0 GPa, and phase transition is sluggish. The orthorhombic phase of nanocrystalline CaF 2 is stable up to 46.5 GPa. The enhancement of transition pressure in CaF 2 nanocrystals as compared with the corresponding bulk material is mainly caused by the surface energy difference between the phases involved.
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