Expanded graphite, valued for its exceptional chemical and thermal stability, serves as an ideal cold cathode material but suffers from limited surface emission sites that impair field emission performance. In recent years, laser irradiation technology has been considered as a surface modification method with great potential. In this study, we used laser irradiation to modify the surface of bulk expanded graphite cathode (BEG). At low laser power, a multilayered graphene structure was formed on the BEG surface, can provide more field emission sites. The efficacy of the method is evidenced by the reduction of turn-on and threshold field strength from 3.24 V/μm and 3.57 V/μm to 2.44 V/μm and 3.14 V/μm, respectively, along with the enhancement of the field enhancement factor to 4006. The maximum current density recorded at 6.8 V/μm was 1248.44 mA/cm2 and the voltage fluctuation rate over a 24-hour period was a mere 1.3 % at 4 mA@0.4A/cm2. The methodology outlined in this study is characterised by its simplicity, efficiency and cost-effectiveness, particularly in the context of large-area vacuum electronic devices.

中文翻译：

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通过激光表面改性增强块体膨胀石墨的场发射性能


膨胀石墨因其卓越的化学和热稳定性而受到重视，是一种理想的冷阴极材料，但表面发射位点有限，会影响场发射性能。近年来，激光辐照技术被认为是一种具有巨大潜力的表面改性方法。在本研究中，我们利用激光辐照对块状膨胀石墨阴极 （BEG） 的表面进行了改性。在低激光功率下，在 BEG 表面形成多层石墨烯结构，可以提供更多的场发射位点。该方法的有效性表现为导通和阈值场强分别从 3.24 V/μm 和 3.57 V/μm 降低到 2.44 V/μm 和 3.14 V/μm，同时场增强因子提高到 4006。在 6.8 V/μm 处记录的最大电流密度为 1248.44 mA/cm2，在 4 mA@0.4A/cm2 处 24 小时内的电压波动率仅为 1.3%。本研究中概述的方法具有简单、高效和成本效益的特点，尤其是在大面积真空电子设备的背景下。