Field electron emission properties of bulk diamond/expanded graphite composite cathode.

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Diamond has negative electron affinity and high thermal conductivity, but high surface resistivity limits cold cathode applications.
• Expanded graphite offers high electrical conductivity and cost-effectiveness, making it a suitable complementary material.
• Hybrid structures combining diamond and expanded graphite are desirable for synergistic field-emitting properties.

Purpose of the Study:

• To prepare diamond-expanded graphite bulk composite cathodes.
• To investigate the electron emission properties of these hybrid materials.
• To optimize the composition for enhanced field emission.

Main Methods:

• Cold pressing method was employed for synthesizing the composite cathodes.
• Characterization of electron emission activity, including turn-on field, threshold field, and current density.
• Evaluation of field enhancement factor.

Main Results:

• The composite cathode with 20% diamond content (0.5 μm particle size) showed optimal electron emission.
• Achieved turn-on field strength of 1.61 V/μm (at 1 mA/cm²) and threshold field strength of 2.11 V/μm (at 10 mA/cm²).
• Maximum current density reached 911.24 mA/cm² at 3.77 V/μm, with a field enhancement factor of 4490.

Conclusions:

• Diamond-expanded graphite composites are effective for field-emitting applications.
• Optimized composition significantly enhances electron emission performance.
• The developed material shows promise for advanced cold cathode technologies.