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Updated: Jun 11, 2025
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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
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Unveiling the boson peaks in amorphous phase-change materials
Jens Moesgaard1, Tomoki Fujita1, Shuai Wei1,2
1Department of Chemistry, Aarhus University, 8000 Aarhus, Denmark.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|September 27, 2024
Summary
Boson peaks, anomalous heat capacity contributions in amorphous solids, are confirmed in phase-change materials (PCMs). Their properties correlate with Sb-content, offering insights into material behavior.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Thermodynamics
Background:
- The boson peak is a universal feature in amorphous solids, affecting low-temperature heat capacity.
- Amorphous phase-change materials (PCMs) like Ge-Sb-Te are crucial for memory applications but their boson peak behavior is unknown.
- Understanding boson peaks in PCMs is vital for correlating low-temperature properties with high-temperature material performance.
Purpose of the Study:
- To investigate the existence and characteristics of boson peaks in amorphous Ge-Sb-Te phase-change materials.
- To determine the relationship between boson peak parameters and alloy composition (Sb-content).
- To explore the broader implications of boson peak behavior in PCMs compared to other amorphous materials.
Main Methods:
- Measurement of heat capacity for pseudo-binary Ge-Sb-Te compositions from low temperatures to liquidus temperatures.
- Analysis of heat capacity data using the Debye model with modifications incorporating an Einstein model to capture boson peak features.
- Correlation analysis of extracted boson peak parameters with Sb-content, glass transition temperature (Tg), and kinetic fragility.
Main Results:
- Pronounced boson peaks were observed in the heat capacity of amorphous Ge-Sb-Te alloys below 10 K across all compositions.
- Characteristic boson peak parameters showed a near-linear correlation with increasing Sb-content.
- Phase-change materials exhibit boson peak correlations with Tg and fragility that are intermediate between metallic and covalent glasses.
Conclusions:
- Boson peaks are present in amorphous phase-change materials and originate from excess vibrational modes of dynamic defects.
- The Sb-content significantly influences the characteristics of these boson peaks.
- Studying boson peaks in PCMs provides a pathway to predict their higher-temperature properties from low-temperature measurements.
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