Mechanochemical Synthesis Enables Melting, Glass Formation and Glass-Ceramic Conversion in a Cadmium-Based Zeolitic...

Area of Science:

• Materials Science
• Inorganic Chemistry
• Solid State Chemistry

Background:

• Metal-organic frameworks (MOFs) are highly versatile materials with tunable properties and diverse applications.
• Zeolitic imidazolate frameworks (ZIFs) represent a subclass of MOFs known for their structural diversity and potential utility.
• Developing new ZIF-based materials, particularly in glassy forms, is crucial for expanding their application scope.

Purpose of the Study:

• To report the synthesis and characterization of the first cadmium-based zeolitic imidazolate framework (ZIF) glass.
• To investigate the effect of mechanochemical synthesis on the properties of Cd(im)2 (imidazolate) precursor.
• To explore the thermal behavior, structural transitions, and potential applications of the resulting ZIF glass and glass-ceramic.

Main Methods:

• Mechanochemical synthesis of sub-micrometer-sized Cd(im)2 particles.
• Melt-quenching of Cd(im)2 particles to form a monolithic glass.
• Differential scanning calorimetry (DSC) to determine glass transition temperature (Tg) and melting points.
• X-ray diffraction (XRD) and other structural analyses to characterize crystalline and glassy phases.
• Thermal analysis to investigate phase behavior and recrystallization.

Main Results:

• Successful preparation of the first cadmium-based ZIF glass via melt-quenching of mechanochemically synthesized Cd(im)2.
• Mechanochemical synthesis reduced crystallite size and melting temperature, facilitating glass formation.
• The resulting ZIF glass exhibits a glass transition temperature (Tg) of 175 °C.
• Partial recrystallization upon reheating yielded a single-component glass-ceramic with enhanced mechanical properties.
• Demonstrated tunability of phase behavior through thermal parameters and linker substitution.

Conclusions:

• This work establishes cadmium-based ZIF glasses, expanding the ZIF glass system to second-row transition metals.
• Mechanochemical synthesis is a valuable tool for tailoring MOF thermal properties and enabling glass formation.
• The dual-phase functionality of the glass-ceramic offers potential for applications in thermal energy storage, phase change memory, and optics.