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Updated: May 23, 2026
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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
Negative thermal expansion in isotropic crystals.
Tong Li1, Martin T Dove1,2,3
1Department of Mechanical Engineering, Guizhou University of Engineering Science, Bijie, 695013, China.
Materials Horizons
|May 22, 2026
Summary
Negative thermal expansion (NTE) in crystals is explained by four key principles: network structure, low-frequency vibrations, vibration distribution, and dynamic disorder. Understanding these principles aids in predicting and designing new NTE materials.
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Negative thermal expansion (NTE) is counterintuitive, as most materials expand when heated.
- Understanding NTE in isotropic crystals has been challenging despite experimental and theoretical advancements.
Purpose of the Study:
- To demystify the phenomenon of negative thermal expansion (NTE) in isotropic crystals.
- To rationalize the existence of NTE and predict its occurrence in new materials.
Main Methods:
- Review of experimental and theoretical investigations on NTE.
- Identification and explanation of four core principles governing NTE in cubic crystals.
- Application of principles to specific examples, including NaZr2(PO4)3.
Main Results:
- NTE in cubic crystals is rationalized by four principles: network structure, low-frequency vibrations, vibration distribution in reciprocal space, and dynamic disorder.
- These principles also apply to anisotropic crystals, with additional factors influencing NTE.
- NTE arises from a balance between mechanisms promoting expansion and contraction.
Conclusions:
- A unified understanding of NTE is achieved through the interplay of four principles and chemical effects.
- The study provides a practical framework for understanding NTE, moving beyond single-mechanism explanations.
- Research on NTE materials has significantly advanced the general understanding of thermal expansion phenomena.
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