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First-Order Liquid-Liquid Transition without Density Discontinuity in Molten Sodium Acetate Trihydrate and Its
Xun Liu1, Shiyu Liu1, Enyi Chen1
1School of Materials Science and Engineering and State Key Lab for Materials Processing and Die and Mold Technology , Huazhong University of Science and Technology , Wuhan 430074 , People's Republic of China.
The Journal of Physical Chemistry Letters
|July 19, 2019
Summary
Researchers observed a liquid-liquid transition in sodium acetate trihydrate, influencing crystallization pathways and enabling crystal polymorph selection. This finding offers new control over crystallization processes.
Area of Science:
- Materials Science
- Physical Chemistry
- Crystallography
Background:
- Liquid-liquid transition (LLT) involves phase changes between distinct liquid states of the same composition.
- Understanding LLT is crucial for comprehending liquid behavior and its influence on crystallization.
- The impact of LLT on crystallization kinetics and product selection remains an area of active research.
Purpose of the Study:
- To investigate the occurrence of a first-order liquid-liquid transition (LLT) in the sodium acetate trihydrate melt above its liquidus temperature.
- To examine the influence of this LLT on the crystallization process, including kinetics and polymorph outcomes.
- To explore the potential of LLT for controlling crystallization pathways and achieving specific crystal polymorphs.
Main Methods:
- Nuclear magnetic resonance (NMR) spectroscopy to probe liquid structure and dynamics.
- Differential scanning calorimetry (DSC) to detect thermal events associated with phase transitions.
- High-precision density measurements to characterize density changes during the LLT.
Main Results:
- A first-order liquid-liquid transition was identified in sodium acetate trihydrate melt above the liquidus temperature.
- The observed LLT exhibited negligible density change.
- The LLT significantly affected the kinetics and product distribution of subsequent crystallization.
Conclusions:
- The study demonstrates the existence and impact of LLT in sodium acetate trihydrate.
- LLT provides a novel mechanism for controlling crystallization pathways.
- This research opens avenues for targeted crystal polymorph selection through manipulation of liquid states.
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