中文摘要：

通过分子动力学模拟两个TiO2纳米颗粒升温烧结过程中的结构演变和烧结颈生长，并基于系统空间网格化和近邻网格种类分析法开发了烧结颈原子识别模型，成功地对烧结颈原子进行识别，结合已开发的表面原子识别模型将系统中原子详细分类，对比不同种类原子在烧结过程中的变化规律。结果表明，温度超过573 K后，烧结明显发生；烧结颈总截面积随烧结温度的增大而增大，烧结颈内侧截面积所占比例较大，烧结颈外侧截面积相对较小且不易受烧结温度影响；烧结颈原子平均位移明显大于母体内部原子和表面原子，且烧结颈原子中O原子迁移活性高于Ti 原子；烧结颈外侧原子平均位移最大，说明烧结颈生长主要依靠外侧原子运动。烧结颈原子识别模型识别有效、稳定，为进一步分析不同区域的结构特性奠定了基础。

英文摘要：

Structure transformation and neck growth during the heat and sintering process of two TiO2 nanoparticles were investigated using molecular dynamics （MD） simulations. Based on the space meshing of the system and analysis of neighboring meshes, a neck atom identification model was developed. The model was successfully applied to identify neck atoms. Combined with the surface atom identification model previously developed by the authors, atoms in the system were further classified and the characteristics of the classified atoms were simulated and analyzed. The results show that sintering occurs when the temperature is above 573 K, the neck area increases with increasing sintering temperature, and it is mostly occupied by interior atoms. Surface atoms occupy less neck area and they are less sensitive to sintering temperature variation. The average displacement of neck atoms is larger than that of surface and interior atoms of the mother particles and O atoms are more active in migration than Ti atoms in the neck. Meanwhile, displacement of outside neck atoms is larger than that of inside neck atoms, meaning that neck growth mainly depends on the motion of outside neck atoms. The proposed model is stable and effective, and it provides fundamental information to analyze nanostructures in different zones.