Plasticity of Metal-Organic Framework Glasses

Area of Science:

• Materials Science
• Solid-state Chemistry

Background:

• Glasses are typically brittle, limiting their use as structural materials.
• Metal-organic frameworks (MOF) offer unique chemical and structural properties.
• MOF glasses present an opportunity to overcome the brittleness of conventional glasses.

Purpose of the Study:

• To investigate the mechanical properties of MOF glasses.
• To determine the plasticity and deformation mechanisms of MOF glasses under uniaxial compression.
• To assess the influence of strain rate on the mechanical behavior of MOF glasses.

Main Methods:

• Strain-rate-dependent uniaxial micropillar compression experiments were conducted.
• Three series of MOF glasses (a_gZIF-62, a_gZIF-UC-5, and a_gTIF-4) with varying linker molecules were tested.
• Yield strength and plastic deformation were measured across a range of strain rates.

Main Results:

• MOF glasses demonstrated substantial plasticity, deforming up to 35% strain at quasi-static rates.
• Yield strength increased with strain rate, with a sensitivity of m = 0.024 for a_gZIF-62.
• Plasticity was observed irrespective of the specific substituting linker molecules used.

Conclusions:

• Structural densification is the primary mechanism responsible for the observed extensive plasticity in MOF glasses.
• The findings challenge the inherent brittleness associated with glasses.
• MOF glasses show potential as robust structural materials.