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通过分子动力学模拟两个TiO_2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。
The structure evolution and sintering neck growth of two TiO 2 nanoparticles during sintering were investigated by molecular dynamics simulation. At the same time, based on the systematic spatial gridding and the near-neighbor grid type analysis, a sintering neck atomic identification model was developed. The atoms in the system are classified in detail according to the developed surface atomic recognition model to compare the variation rules of different kinds of atoms in the sintering process. The results show that the sintering takes place obviously when the temperature exceeds 573 K; the total cross section area of the sintered neck increases with the increase of the sintering temperature, and the cross sectional area of the inner side of the sintered neck is larger, and the cross sectional area of the outer side of the sintered neck is relatively small, Sintering temperature. The average displacement of sintering neck is obviously larger than that of the internal atoms and surface atoms. The migration of O atoms in the sintering neck is higher than that of Ti. The average displacement of the outer side of the sintering neck is the largest, which shows that the growth of the sintering neck mainly depends on the movement of the outer atoms. The identification of sintering neck atom recognition model is effective and stable, which lays the foundation for further analysis of the structural characteristics of different regions.