Polymer matrix ferroelectric composites under pressure: Negative electric capacitance and glassy dynamics

Area of Science:

• Materials Science
• Condensed Matter Physics
• Dielectric Spectroscopy

Background:

• Polyvinylidene difluoride (PVDF) and barium strontium titanate (BST) are key materials in dielectric applications.
• Understanding composite behavior under extreme conditions is crucial for advanced material design.
• Dielectric spectroscopy is a powerful tool for probing material dynamics.

Purpose of the Study:

• To investigate the high-pressure dielectric properties of BST/PVDF composites.
• To elucidate the relationship between temperature-dependent and pressure-dependent relaxation dynamics.
• To explain the emergence of negative electric capacitance in these composites.

Main Methods:

• Broadband dielectric spectroscopy was employed.
• Experiments were conducted under varying high pressures, reaching the GPa domain.
• Measurements were performed on composites of polyvinylidene difluoride (PVDF) and barium strontium titanate (BST) microparticles.

Main Results:

• A coupling between Arrhenius temperature-dependent dynamics and Super-Arrhenius/Super-Barus pressure-dependent relaxation times was observed.
• The unique behavior of the BST/PVDF composite was explained based on these findings.
• The negative electric capacitance phenomenon was identified as pressure increased towards the GPa range.

Conclusions:

• The study provides insights into the complex dielectric response of BST/PVDF composites under high pressure.
• The findings suggest a novel mechanism for negative capacitance in dielectric materials.
• This research opens avenues for developing new materials with tunable electrical properties for high-pressure applications.