Centimeter-sized diamond composites with high electrical conductivity and hardness

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Achieving high-performance materials with both superior mechanical properties and electrical conductivity, especially in bulk forms, is a significant challenge due to inherent trade-offs.
• Existing methods often require extreme conditions, limiting scalability and applications.

Purpose of the Study:

• To synthesize centimeter-sized diamond/graphene composites with enhanced mechanical and electrical properties.
• To explore synthesis under moderate pressure and temperature conditions.
• To overcome the trade-off between mechanical strength and electrical conductivity in bulk materials.

Main Methods:

• Utilized nanodiamonds as precursors for composite synthesis.
• Employed moderate pressure (12 GPa) and temperature (1,300–1,500 °C) conditions.
• Characterized the resulting composites for microstructure, electrical conductivity, hardness, and toughness.

Main Results:

• Synthesized centimeter-sized diamond/graphene composites composed of ultrafine diamond grains and few-layer graphene domains.
• Achieved remarkable electrical conductivity of 2.0 × 10⁴ S m^-1 at room temperature.
• Obtained high Vickers hardness (~55.8 GPa) and toughness (10.8–19.8 MPa m^1/2).

Conclusions:

• The synthesis of diamond/graphene composites under moderate conditions is feasible due to a lower graphitization energy barrier.
• These findings enable the development of large-sized diamond-based materials with simultaneous ultrahigh electrical conductivity and superior mechanical properties.
• The study paves the way for broad applications of these advanced materials.