Percolation-Triggered Negative Permittivity in Nano Carbon Powder/Polyvinylidene Fluoride Composites

Area of Science:

• Materials Science
• Condensed Matter Physics

Background:

• Percolating composites with negative permittivity are crucial for electromagnetic shielding and electronic devices.
• Carbon powder/polyvinylidene fluoride (CP/PVDF) composites are explored for their dielectric properties.

Purpose of the Study:

• To fabricate CP/PVDF percolating composites exhibiting negative permittivity.
• To investigate the relationship between CP content, percolation, and electromagnetic properties.

Main Methods:

• Fabrication of CP/PVDF composites with varying CP content.
• Analysis of phase composition, microstructure, AC conductivity, and relative permittivity.
• Characterization of Drude-type negative-permittivity behavior.

Main Results:

• CP/PVDF composites exhibit Drude-type negative permittivity above the percolation threshold due to plasmonic state formation.
• A significant conductivity increase (two orders of magnitude) occurs at 12.5 wt% CP, coinciding with percolation.
• A composite with 5 wt% CP shows high permittivity (31.5) and low dielectric loss (tanδ < 0.2).

Conclusions:

• The study demonstrates the potential of CP/PVDF composites for electromagnetic applications.
• The observed phenomena are linked to the formation of an interconnected carbon network and electron delocalization.
• These findings offer new possibilities for PVDF-based materials in electromagnetic shielding and antenna design.