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Local atomic structure in equilibrium and supercooled liquid Zr(75.5)Pd(24.5)
1Department of Physics, Washington University, St. Louis, Missouri 63130, USA. nmauro@physics.wustl.edu
The Journal of Chemical Physics
|August 3, 2012
Summary
Atomic structures in supercooled liquids were studied using advanced diffraction. Researchers found medium-range order and icosahedral-like clusters, especially in palladium-palladium interactions, persisting across temperatures.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Understanding liquid atomic structures is crucial for materials design.
- Eutectic alloys like Zr-Pd exhibit complex liquid-state behavior.
- Containerless processing is vital for studying reactive liquid metals.
Purpose of the Study:
- To investigate the atomic structure of eutectic Zr(75.5)Pd(24.5) liquids.
- To determine the presence and nature of medium-range order (MRO) and local order.
- To analyze structural evolution with temperature in equilibrium and supercooled states.
Main Methods:
- In situ high-energy synchrotron diffraction.
- Beamline electrostatic levitation (BESL) technique for containerless processing.
- Reverse Monte Carlo (RMC) fitting combined with ab initio molecular dynamics (AIMD) simulations.
Main Results:
- Evidence of medium-range order (MRO) characterized by strong palladium-palladium (solute-solute) avoidance.
- MRO was observed across a wide temperature range, from above the liquidus to deep supercooling.
- A modest degree of icosahedral-like local order around palladium atoms was quantified, with increased face-sharing at lower temperatures.
Conclusions:
- The study reveals significant MRO in Zr-Pd liquids, challenging simple liquid models.
- Icosahedral-like clusters and their tendency to form extended structures are temperature-dependent.
- Containerless diffraction and AIMD are powerful tools for probing complex liquid structures.
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