Synthesis and properties of mirror-like large-grain graphite films

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Large-grained graphite films are desirable but often contain defects due to synthesis methods.
• Existing techniques using metal catalysts result in wrinkled graphite with degraded properties.

Purpose of the Study:

• To synthesize mirror-like, large-grained graphite films with controllable dimensions and minimal defects.
• To overcome the limitations of current methods producing wrinkled and defective graphite.

Main Methods:

• Utilized flat Ni-Mo alloy melts as catalysts, matching the dimensions of the metal foils.
• Controlled substrate-graphite film interaction by deliberate nickel evaporation, creating a porous substrate.
• Characterized graphite film properties including stacking, grain size, electrical conductivity, mechanical strength, and thermal conductivity.

Main Results:

• Synthesized mirror-like graphite films with few nano kinks and millimeter-sized grains.
• Achieved 100% AB-stacked graphite with grain sizes exceeding highly oriented pyrolytic graphite.
• Obtained high electrical conductivity (2.25 × 10⁴ S cm⁻¹), Young's modulus (969 ± 69 GPa), fracture strength (1.29 ± 0.203 GPa), and thermal conductivity (2034.4 ± 68 W m⁻¹ K⁻¹).

Conclusions:

• The Ni-Mo alloy melt method enables the production of high-quality, large-grained graphite films.
• The resulting graphite films exhibit exceptional properties suitable for advanced electronic and mechanical applications.
• This technique offers a pathway to defect-free, large-scale graphite film synthesis.