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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Mixing effects in the crystallization of supercooled quantum binary liquids
M Kühnel1, J M Fernández2, F Tramonto3
1Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany.
The Journal of Chemical Physics
|August 17, 2015
Summary
Neon impurities significantly slow down the crystallization of quantum liquids like parahydrogen (pH2) and orthodeuterium (oD2). This effect correlates with quantum delocalization and alters crystal structure, with neon initiating freezing.
Area of Science:
- Quantum fluid dynamics
- Low-temperature physics
- Spectroscopy
- Materials science
Background:
- Supercooled quantum liquids, such as parahydrogen (pH2) and orthodeuterium (oD2), exhibit unique properties due to quantum effects.
- Understanding crystallization kinetics and structure in these systems is crucial for fundamental physics and potential applications.
- Previous studies indicated that mixtures of pH2 and oD2 influence crystallization, but the role of non-reactive impurities was less clear.
Purpose of the Study:
- To investigate the effect of neon (Ne) impurities on the crystallization process of supercooled parahydrogen (pH2) and orthodeuterium (oD2) liquid mixtures.
- To determine how Ne impurities influence the kinetics (growth rates) and structure of the resulting crystals.
- To explore the relationship between quantum delocalization effects, particle size, and crystallization behavior in the presence of impurities.
Main Methods:
- Raman spectroscopy was employed to study the crystallization of liquid microjets composed of pH2 or oD2 diluted with Ne.
- Experimental data on crystal growth rates were collected under supercooled conditions.
- Path-integral simulations were performed to model the behavior of the supercooled liquid mixtures and correlate with experimental findings.
Main Results:
- The introduction of Ne impurities significantly reduced the crystal growth rates of both pH2 and oD2.
- A correlation was observed between the measured growth rates and the ratio of effective particle sizes, influenced by quantum delocalization.
- The crystalline structure of the mixtures was substantially altered by the presence of Ne, with evidence suggesting Ne-rich crystallites initiate freezing.
Conclusions:
- Neon impurities act as significant modifiers of crystallization kinetics in supercooled quantum liquids, slowing down crystal growth.
- Quantum delocalization and effective particle size ratios play a key role in the observed crystallization dynamics.
- Neon impurities likely serve as nucleation sites, influencing the final crystalline structure of parahydrogen and orthodeuterium mixtures.
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