Geometric indicators of local plasticity in glasses measured by scanning small-beam diffraction

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid Mechanics

Background:

• Defects in crystalline solids are crucial for understanding material properties like growth and deformation.
• The Burgers vector quantifies lattice distortions and slip in crystals relative to a known reference structure.
• Glasses lack the periodicity of crystals, posing challenges in defining a reference state for deformation analysis.

Purpose of the Study:

• To investigate the utility of structural parameters derived from diffraction for probing deformation in glasses.
• To identify robust metrics for characterizing plastic events in amorphous materials.
• To explore the applicability of the Burgers vector concept to disordered glass structures.

Main Methods:

• Analysis of structural parameters obtained from diffraction measurements of glasses.
• Examination of coordinated transformations in local particle arrangement centrosymmetry as markers of plastic events.
• Investigation of two geometric indicators: continuous Burgers vector and quadrupolar strain, derived from local distortions before and after deformation.

Main Results:

• Coordinated transformations in local particle arrangement centrosymmetry serve as strong indicators of plastic events in glasses.
• The continuous Burgers vector emerges as a sensitive and robust metric for quantifying local structural transformations due to mechanical deformation in glasses.
• Deformation in glasses can be effectively characterized using geometric indicators, even in the absence of a well-defined periodic reference state.

Conclusions:

• The Burgers vector is a valuable tool for understanding local structural changes and plastic deformation in disordered glasses.
• Geometric indicators derived from local distortions provide insights into the mechanical behavior of amorphous materials.
• This study extends the application of concepts traditionally used for crystalline defects to the realm of glasses.