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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Deuteron spin lattice relaxation in amorphous ices
M Scheuermann1, B Geil, K Winkel
1Institut für Festkörperphysik, TU Darmstadt, Hochschulstrasse 6, 64289 Darmstadt, Germany. marco.scheuermann@physik.tu-darmstadt.de
The Journal of Chemical Physics
|June 21, 2006
Summary
Deuteron spin lattice relaxation times T(1) reveal distinct amorphous water states. These findings help understand water
Area of Science:
- Physical Chemistry
- Materials Science
- Thermodynamics
Background:
- Amorphous solid water exists in various forms, including low-density (LDA), high-density (HDA), and very high-density (VHDA) states.
- Understanding the transitions and stability of these amorphous water states is crucial for various scientific disciplines.
- Deuteron spin lattice relaxation times (T(1)) offer insights into molecular dynamics and structural properties.
Purpose of the Study:
- To investigate the temperature-dependent deuteron spin lattice relaxation times (T(1)) in LDA, HDA, and VHDA states of water.
- To utilize T(1) as a monitor parameter for studying the kinetics of transitions between amorphous water states.
- To elucidate the nature of intermediate states formed during the annealing of VHDA and HDA.
Main Methods:
- Measurement of temperature-dependent deuteron spin lattice relaxation times (T(1)) for water in LDA, HDA, and VHDA states at ambient pressure.
- Analysis of magnetization recovery curves to determine the monoexponential nature of relaxation.
- Comparison of T(1) values across different amorphous states and during phase transitions.
Main Results:
- Magnetization recovery in all amorphous water states was found to be essentially monoexponential.
- LDA exhibited significantly longer T(1) values compared to HDA and VHDA.
- During VHDA to LDA transformation, an intermediate HDA-like state was identified via its T(1) characteristics.
- The transition from VHDA to the HDA-like state and subsequently to LDA occurred at temperatures above the kinetic stability limit of native HDA.
Conclusions:
- Spin lattice relaxation time (T(1)) serves as an effective monitor for the kinetics of amorphous water state transitions.
- The annealing of VHDA at ambient pressure results in a relaxed HDA-like state, reinforcing current views on amorphous water structures.
- The observed transition temperatures provide critical data for understanding the thermodynamic and kinetic landscapes of amorphous water.
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