Metal-Organic Crystallized Glasses: Microstructure Formation and Their Properties

Area of Science:

• Materials Science
• Crystallography
• Solid-State Chemistry

Background:

• Glass-ceramics offer unique properties through controlled partial crystallization.
• This approach has historically been confined to inorganic glass systems.
• Metal-organic frameworks (MOFs) present a new class of amorphous materials for glass-ceramic development.

Purpose of the Study:

• To introduce and characterize metal-organic crystallized glasses (MOCGs).
• To investigate the influence of annealing on crystallinity and properties of MOF glasses.
• To explore the potential for tuning dielectric and conductive properties in MOCGs.

Main Methods:

• Preparation of 2D Cd(H2PO4)2(1,2,4-triazole)2-based MOF glasses.
• Controlled annealing above the glass transition temperature (Tg) to induce partial crystallization.
• Characterization of MOCGs using techniques to determine crystallinity, crystallite size, micromechanical properties, dielectric constants, and proton conductivity.
• Exploration of mixed-metal MOF glass systems for solid solution formation.

Main Results:

• Successfully fabricated MOCGs by controlling crystallization in MOF glasses.
• Demonstrated tunable micromechanical properties, dielectric constants, and proton conductivities via annealing.
• Achieved a 15% crystalline MOCG with a dielectric constant 10x higher than parent glass/crystals.
• Extended the concept to mixed-metal systems, showing solid solution formation during annealing.

Conclusions:

• Metal-organic crystallized glasses (MOCGs) represent a new class of functional materials.
• Partial crystallization of MOF glasses provides a pathway to engineer material properties.
• MOCGs offer significant potential for applications requiring high dielectric constants and tailored conductivity.