Negative Volume Compressibility in Sc₃N@C₈₀-Cubane Cocrystal with Charge Transfer

Area of Science:

• Materials Science
• Solid-State Physics
• Chemistry

Background:

• Materials typically contract under pressure due to thermodynamic laws.
• Negative compressibility, where materials expand under pressure, has been theoretically predicted but rarely observed.

Purpose of the Study:

• To investigate the pressure-induced behavior of a novel cocrystal composed of a metallofullerene and cubane.
• To explore the potential for anomalous negative volume compressibility in engineered materials.

Main Methods:

• Synthesis of a cocrystal featuring Sc3N@C80 metallofullerene and energetic cubane.
• High-pressure experiments to observe structural and volumetric changes.
• Analysis of molecular transformations under varying pressure conditions.

Main Results:

• The cocrystal exhibits anomalous negative volume compressibility.
• Sc3N@C80 remains stable, while cubane molecules undergo configurational transformations above 6.5 GPa.
• A volume expansion of approximately 1.8% is observed at higher pressures due to cubane's low-density configuration.

Conclusions:

• The engineered cocrystal demonstrates a rare phenomenon of negative volume compressibility.
• This finding validates theoretical predictions and suggests potential applications in mechanical metamaterials.
• The study highlights the role of molecular transformations in achieving unusual material properties.