Abstract:

Chlorinated titanium dioxide is an important inorganic raw material for chemical industry and energy storage, and its properties are controlled by multiple factors such as sintering heat treatment. Traditional experimental methods are difficult to accurately quantify and analyze the sintering process, and molecular dynamics simulations can accurately assess the dynamic evolution of sintering from the atomic scale, but the existing studies are relatively single-limit for the mechanistic interpretation of factors such as temperature, particle size and arrangement. A non-isotropic multi-particle model and effective characterization parameters such as sintering neck size, Lindemann index and apparent activation energy were introduced, and the effects of temperature, particle size and arrangement on the sintering behavior of TiO₂ nanoparticles were investigated by molecular dynamics simulation system. The results showed that increasing the temperature was conducive to stimulating intense atomic migration and diffusion and accelerating the densification process of the sintered body. When the temperature was the same, the sintering rate of TiO₂ nanoparticles with smaller particle size was faster, but it was easy to be absorbed and fused by the particles with larger particle size. In addition, the particle arrangement also affected the sintering behavior with the stacked arrangement having a more obvious sintering advantage than the linear arrangement. The initial stage of sintering was mainly through surface diffusion growth, while the later stage was through grain boundary diffusion densification. The results were of guiding significance for optimizing industrial sintering parameters and preparing high-performance nanomaterials.

Key words: titanium dioxide, nanoparticles, sintering, molecular dynamics simulation, diffusion

摘要：

氯化钛白是化工、储能等领域重要的无机原料，其性能受到烧结热处理等多因素控制。传统实验手段难以准确量化烧结过程，而分子动力学模拟能从原子尺度准确评估烧结的动态演化过程，但现有研究对诸如温度、粒度、排列方式等因素的机理阐释比较单一局限。本文引入非等径多颗粒模型、烧结颈尺寸、Lindemann指数和表观活化能等有效表征参数，通过分子动力学模拟系统研究了温度、粒度及排列方式对TiO₂纳米颗粒的烧结行为的影响。结果表明，升高温度有利于激发剧烈的原子迁移扩散，加速烧结体的致密化进程。温度相同时，较小粒径的TiO₂纳米颗粒烧结速率更快，但易被较大粒径颗粒吸收融合。此外，颗粒排列方式也会影响烧结行为，堆垛排列比线性排列有更明显的烧结优势。烧结初期主要通过表面扩散生长，而后期通过晶界扩散致密化。研究结果对优化工业烧结参数、制备高性能纳米材料具有指导意义。

关键词: 二氧化钛, 纳米粒子, 烧结, 分子动力学模拟, 扩散