Beyond geometry orders: uncovering bonding-heterogeneity-dominated structure-relaxation coupling in glasses

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• The microstructure-property relationship is well-established for crystalline materials.
• Linking amorphous structures to macroscopic properties remains challenging, with traditional geometric analyses often proving insufficient.
• Understanding amorphous material behavior requires exploring factors beyond simple atomic packing.

Purpose of the Study:

• To investigate the factors governing secondary relaxations in amorphous metallic glasses.
• To demonstrate the limitations of geometric packing in predicting properties of amorphous systems.
• To establish the role of electronic structure and chemical bonding in amorphous material dynamics.

Main Methods:

• Experimental analysis of two Palladium-based metallic glasses with similar geometries but different relaxations.
• Electronic structure analysis to identify differences in bonding and network development.
• Integration of experimental data with deep-learning simulations.

Main Results:

• Identical geometries in the studied metallic glasses masked distinct secondary relaxation behaviors.
• Electronic structure analysis revealed weaker Cu-P bonds and a less developed covalent network in one glass, enabling string-like atomic motions and pronounced relaxation.
• Stronger Ni-P interactions in the other glass resulted in a more constrained network and limited relaxation.
• Local bonding heterogeneity, influenced by electronic interactions, was identified as the key differentiator.

Conclusions:

• Electronic interactions and bonding fluctuations are critical determinants of glass dynamics, surpassing purely geometric considerations.
• A new paradigm for amorphous material design should prioritize electronic structure and chemical bonding over geometric order.
• This work bridges the gap between local chemical heterogeneity and macroscopic behavior, advancing glass physics.