Koparde Vishal N, Cummings Peter T
Department of Chemical Engineering, Vanderbilt University, VU Station B 351604, Nashville, Tennessee 37235, USA.
J Phys Chem B. 2005 Dec 29;109(51):24280-7. doi: 10.1021/jp054667p.
Nanoparticles have been an area of active research in recent years due to their properties, which can be greatly different from the bulk. In this work, we study the sintering of TiO2 nanoparticles using molecular dynamics simulations. Such sintering occurs in flame reactors where nanotitania is prepared via the chloride process. Decrease in free energy due to reduction in surface area is the main driving force for sintering of particles. Simulations, at various starting temperatures and orientations, indicate that the process of sintering is strongly affected by temperature and initial orientation. Extremely high diffusion of ions in the neck region of sintering nanoparticles supports the idea that solid-state diffusion is significant in metal-oxide nanoparticle sintering. It is found that the dipole-dipole interaction between sintering nanoparticles plays a very important role at temperatures away from the melting point. The duration of the simulation is not enough to observe the complete sintering process, but important initial stages are well studied.
近年来，纳米颗粒因其性质与块状材料有很大不同而成为一个活跃的研究领域。在这项工作中，我们使用分子动力学模拟研究了TiO₂纳米颗粒的烧结过程。这种烧结发生在通过氯化法制备纳米二氧化钛的火焰反应器中。由于表面积减小导致的自由能降低是颗粒烧结的主要驱动力。在不同起始温度和取向条件下进行的模拟表明，烧结过程受温度和初始取向的强烈影响。烧结纳米颗粒颈部区域离子的极高扩散支持了固态扩散在金属氧化物纳米颗粒烧结中起重要作用的观点。研究发现，在远离熔点的温度下，烧结纳米颗粒之间的偶极 - 偶极相互作用起着非常重要的作用。模拟的持续时间不足以观察到完整的烧结过程，但重要的初始阶段已得到充分研究。
