Characterization and field emission properties of multi-walled carbon nanotubes with fine crystallinity prepared by CO2 laser ablation

Multi-walled carbon nanotubes (MWNTs) were synthesized by irradiating of a CO2 laser in continuous wave mode onto a boron-containing graphite target at room temperature. The pressure of Ar atmosphere was controlled in 50, 150, 400, or 760 Torr. The diameter of obtained MWNTs was in the range of 5–40 nm. The quantity and degree of graphitization of synthesized MWNTs increased with the Ar gas pressure. A large quantity of MWNTs with fine crystalline structure has been synthesized preferentially at the condition of 760 Torr. The MWNTs with the fine crystalinity indicated highly oxidative stability in O2. We also found that a large area field emission device with MWNT cathodes indicated good β value of 3.6 × 104 cm−1, and sufficient reliability for long term operations over 150 h, suggesting promising application to field emission devices.