Nanoparticle dynamics in the spatial afterglows of nonthermal plasma synthesis reactors
Nanoparticle dynamics in the spatial afterglows of nonthermal plasma synthesis reactors
复制标题
DOI：
10.1016/j.cej.2020.128383
复制
发表时间：
2021-01-16
影响因子：
15.1
通讯作者：
Hogan, Christopher J., Jr.
中科院分区：
文献类型：
--
作者：
Chen, Xiaoshuang;Hogan, Christopher J., Jr.
非热等离子体流管反应器是用于生产基于纳米纤维（NC）的材料和涂层的工业可扩展系统。非热等离子体合成的一个关键优点是在单个反应器中合成NC和存款膜的能力，因为在反应器出口处，NC可以惰性地沉积到目标基底上。沉积颗粒的尺寸和形态会显著影响薄膜的结构和功能。虽然NC通常是近球形的和单分散的，如在等离子体合成反应器中产生的，NC电荷和生长动力学可以被改变时，NC被采样出等离子体和通过空间余辉区域，影响沉积。实验已经证明了空间余辉中NC尺寸和电荷的变化;然而，这些动力学仍然没有通过理论和模拟进行探索和解释。为了解决这个问题，我们开发了一个常数蒙特卡罗（CNMC）模拟模型来研究等离子体流管反应器的空间余辉中的NC放电和增长的机制。NC和等离子体物种之间的碰撞，扩散沉积，和电子解吸从NC被纳入CNMC模拟。模拟结果进行了具体的比较与以前的实验从低压Ar-SiH 4非热等离子体反应器中合成的Si NCs。实验模型的比较表明，CNMC模型可以实现精确的模型NC尺寸分布演变的空间余辉。同时，结果表明，改进的碰撞模型，高能物种扩散模型，电子解吸模型将是必要的，以准确地描绘空间余辉的NC动力学。
Nonthermal plasma flow tube reactors are industrially scalable systems for the production of nanocrystal (NC) based materials and coatings. One key advantage of nonthermal plasma synthesis is the ability to both synthesize NCs and deposit films in a single reactor, as at the reactor outlet, NCs can be inertially deposited onto a target substrate. The size and morphology of deposited particles can substantially influence the film structure and function. Though NCs are typically near-spherical and monodispersed as-produced in plasma synthesis reactors, NC charge and growth dynamics can be altered substantially when NCs are sampled out of the plasma and through the spatial afterglow region, affecting deposition. Experiments have demonstrated changes of NC size and charge in the spatial afterglow; however, these dynamics remain unexplored and unexplained via theory and simulation. To address this, we developed a constant number Monte Carlo (CNMC) simulation model to examine the mechanisms of NC decharging and growth in the spatial afterglow of plasma flow tube reactors. Collisions between NC and plasma species, diffusive deposition, and electron desorption from NCs are incorporated in the CNMC simulation. The simulation results are specifically compared with previous experiments on Si NCs synthesized from a low pressure Ar-SiH4 nonthermal plasma reactor. The experiment-model comparison shows that CNMC models can be implemented which accurately model NC size distribution evolution in a spatial afterglow. Simultaneously, results show that improved collision models, energetic species diffusion models, and electron desorption models will be necessary to accurately depict NC dynamics in spatial afterglows.