Compression Induced Deformation Twinning Evolution in Liquid-Like Cu₂Se.

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Materials Science

Background:

• Copper selenide (Cu2Se) is a promising thermoelectric material with unique liquid-like behavior.
• Understanding structure-property relationships in Cu2Se is crucial for its practical applications.
• The behavior of Cu2Se under mechanical stress at high temperatures remains underexplored.

Purpose of the Study:

• To investigate the structural evolution of beta-copper selenide (β-Cu2Se) under uniaxial compression.
• To determine how temperature influences the mechanical response and structural stability of Cu2Se.
• To elucidate the micromechanisms governing deformation and restructuring in liquid-like Cu2Se.

Main Methods:

• Molecular dynamics simulations were employed to study β-Cu2Se.
• Simulations covered a temperature range of 400–1000 K under uniaxial compression.
• Analysis focused on structural changes, deformation modes, and the role of ion diffusion.

Main Results:

• Above 800 K, Cu2Se exhibits a hybrid structure with a stable Se sublattice and mobile Cu ions.
• Uniaxial loading induces structural heterogeneity, relieved by diffusion-assisted accommodation.
• Increasing strain leads to compression-shear deformation and twinning, with higher temperatures promoting twinning.

Conclusions:

• Higher temperatures enhance structural instability and facilitate deformation twinning in liquid-like Cu2Se.
• Copper diffusion plays a key role in the mechanical modulation and structural adaptation of Cu2Se.
• These findings offer insights into the micromechanisms of hybrid structure evolution and provide a theoretical basis for designing advanced Cu2Se thermoelectric materials.