激光技术, 2016, 40 (1): 25, 网络出版: 2016-03-24   

激光法制备超细纳米金刚石的相变机理

Phase growth mechanism of ultra-fine nano-diamond prepared by nanosecond laser
作者单位
江苏大学 机械工程学院, 镇江 212013
摘要
为了研究激光法制备纳米金刚石的相变机理, 采用纳秒脉冲激光冲击微米级石墨悬浮液, 并做强酸高温氧化提纯处理, 结合X射线衍射、喇曼光谱、高分辨率透射电镜等表征手段以及热力学和动力学分析方法, 对实验结果进行了理论分析和实验验证。合成得到分散均匀、尺寸在4nm~12nm的超细纳米金刚石。结果表明, 纳秒激光辐照下, 石墨是通过固态-气态-液态-固态的形式转变为金刚石结构的; 与毫秒脉冲激光相比, 高功率密度、短脉宽的纳秒激光为金刚石核的生长提供了大的过冷度, 提高了金刚石的形核率和生长速率; 但是纳米金刚石的生长温度范围极小, 冷却过程中石墨结构与金刚石结构同时形核、长大, 引起金刚石颗粒表面的石墨化, 限制了纳米金刚石的生长。
Abstract
In order to study the growth mechanism from graphite to nano-diamond by laser processing, micron graphite suspension was irradiated by nanosecond pulse laser and then was purified by acid high-temperature oxidation. X-ray diffraction, Raman spectroscopy and high-resolution transmission electron microscopy were used in theoretical analysis and experimental verification. The formation mechanism of nano-diamond was analyzed from thermodynamics and kinetics aspects respectively. Ultra-fine nano-diamond with particle size of 4nm~12nm and uniformly dispersion was synthesized. The results show that under the irradiation of nanosecond pulse laser, the transition from graphite to diamond is solid-vapor-liquid-solid phase transformation process. Compared with millisecond pulse laser, nanosecond laser with high intensity and short pulse width can supply larger super-cooling degree for diamond core growth and improve nucleation rate and growth velocity of nano-diamond. However, growth temperature range of nano-diamond is extremely small. Inevitable graphitization on the surface of diamond particles limits the further growth of nano-diamond.

郑腊梅, 吕豫文, 唐少雄, 戴文杰, 随赛, 任旭东. 激光法制备超细纳米金刚石的相变机理[J]. 激光技术, 2016, 40(1): 25. ZHENG Lamei, L Yuwen, TANG Shaoxiong, DAI Wenjie, SUI Sai, REN Xudong. Phase growth mechanism of ultra-fine nano-diamond prepared by nanosecond laser[J]. Laser Technology, 2016, 40(1): 25.

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