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针对激光烧蚀碳悬浮液以及液体介质中的石墨靶形成不同尺寸大小的纳米金刚石,对金刚石颗粒的形成进行了分析。基于激光器参数以及合成条件比较分析了两种烧蚀产生的物理化学差异,并根据热力学条件计算了金刚石颗粒的平衡尺寸和激光烧蚀后形成的碳团簇的冷却速度以及Wilson-Frenkel生长定律进一步计算了纳米金刚石的生长速度、生长时间、生长尺寸。计算结果表明,不同参数的激光烧蚀条件下产生的高温高压碳团簇的大小和密度决定了冷却速度以及生长时间,并最终决定了纳米金刚石尺寸。另外根据金刚石晶体最低能量计算结果也验证了超细纳米金刚石形成的理论基础。动力学与热力学理论计算结果和实验结果相一致,合理解释了不同尺寸纳米金刚石的形成。
The formation of diamond particles was analyzed by laser ablation of carbon suspension and graphite target in a liquid medium to form nano-diamond of different sizes. Based on the laser parameters and the synthesis conditions, the differences between the two kinds of ablation were analyzed. The equilibrium size of the diamond particles and the cooling rate of the carbon clusters formed after the laser ablation were calculated according to the thermodynamic conditions and the Wilson-Frenkel growth law The growth rate, growth time and growth size of nano-diamond were calculated. The calculated results show that the size and density of the high temperature and high pressure carbon clusters generated by laser ablation under different parameters determine the cooling rate and the growth time, and finally determine the size of the nano-diamond. In addition, the calculation results of the minimum energy of diamond crystal also verify the theoretical basis of the formation of ultrafine nanodiamonds. Kinetic and thermodynamic calculations are in good agreement with the experimental results, explaining the formation of nano-sized diamonds with different sizes.