Abstract:

Iron oxide is an important raw material in the fields of chemical industry, metallurgy and energy, and its sinterability at high temperature is crucial to product performance. In this study, the sintering mechanism of Fe₂O₃ nanoparticles was investigated by molecular dynamics simulation (MDS) at different temperatures, particle sizes and vacancy defect concentrations. The results showed that when the particle size of Fe₂O₃ nanoparticles increased from 3 nm to 5 nm, the post-sintering shrinkage decreased from 25.0% to 10.8%, and the relative neck width decreased from 96.6% to 49.5%. When the temperature was increased from 900 K to 1300 K, the atomic diffusion coefficient for the sintering process increased from 1.758 × 10^-3 nm²/ps to 4.303 × 10^-3 nm²/ps, which was increased to 2.45 times. Atomic migration at high temperature (1300 K) transformed some of the particle structures from HCP and BCC structures to amorphous structures with 66.7% of amorphous atoms. The diffusion activation energy of the sintering process of nanoparticles containing 10.0% initial vacancy defect concentration was reduced by about 63.5% compared with that of perfect crystals (0 vacancy concentration), and the atom mobility and sintering densification were enhanced. The above results are of great significance for the optimization of the high-temperature heat treatment process of iron oxide particles.

Key words: Fe₂O₃ nanoparticles, vacancy defects, sintering mechanism, atomic migration, molecular dynamics simulation

摘要：

氧化铁是化工、冶金和能源等领域重要的原料，其在高温下的烧结性对产品性能至关重要。通过分子动力学模拟（MDS）研究了不同温度、粒径与空位缺陷浓度条件下Fe₂O₃纳米颗粒的烧结机制。结果表明，Fe₂O₃纳米颗粒粒径由3 nm增加至5 nm，烧结后收缩率由25.0%降低至10.8%，相对颈部宽度由96.6%降低至49.5%。当温度由900 K升高至1300 K，烧结过程原子扩散系数由1.758×10^-3 nm²/ps增至4.303×10^-3 nm²/ps，增大1.45倍。高温下（1300 K）原子迁移使颗粒部分结构由HCP和BCC结构转变为非晶结构，非晶原子比例为66.7%。含10.0%初始空位缺陷浓度纳米颗粒烧结过程的扩散活化能相比完美晶体（0空位浓度）降低约63.5%，原子迁移性及烧结致密化程度增强。研究结果对氧化铁颗粒高温热处理工艺优化具有指导意义。

关键词: Fe₂O₃纳米颗粒, 空位缺陷, 烧结机制, 原子迁移, 分子动力学模拟