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16:24
Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
A limit of stability in supercooled liquid clusters
Eduardo Mendez-Villuendas1, Ivan Saika-Voivod, Richard K Bowles
1Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
The Journal of Chemical Physics
|October 24, 2007
Summary
Researchers studied the free energy landscape of supercooled gold nanoclusters. They found that freezing becomes a barrierless process at low temperatures, challenging existing theories.
Area of Science:
- Physical Chemistry
- Materials Science
- Nanotechnology
Background:
- Supercooled liquids can exhibit metastable phases.
- Understanding the stability limits of these phases is crucial for predicting material behavior.
- Gold nanoclusters provide a model system for studying phase transitions at the nanoscale.
Purpose of the Study:
- To investigate the free energy landscape of the metastable liquid phase in supercooled gold nanoclusters.
- To determine the limit of stability for the liquid phase.
- To compare experimental findings with mean-field theory predictions.
Main Methods:
- Utilizing the largest solidlike embryo as an order parameter to study the free energy landscape.
- Calculating the rate of nucleation independently from free energy calculations.
- Analyzing the temperature dependence of nucleation rates.
Main Results:
- The free energy landscape shows a local minimum and a maximum at critical embryo sizes just below freezing.
- At 660 K, the free energy becomes monotonically decreasing, indicating the limit of stability.
- The critical embryo size remains finite near the limit of stability, contrary to mean-field predictions.
- Nucleation rates increase rapidly as the free energy barrier approaches kT.
Conclusions:
- The study identifies the limit of stability for supercooled gold nanoclusters.
- Findings challenge mean-field theory predictions regarding critical embryo size.
- Observed nucleation behavior supports the hypothesis of barrierless freezing at low temperatures.
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