Abstract It has been known that morphology and size could affect the properties of crystalline magnetite (Fe3O4). However, specific principle for a simple and predictable way to control them was still absent. Alkali concentration has been demonstrated to be an influential factor on the morphology changes in an ethylene glycol/diethylene glycol (EG/DEG) binary solvothermal system. In this work, crystalline Fe3O4 nanoparticles with a variety of morphologies including clusters, solid spheres, octahedron, truncated-octahedrons, tetrakaidecahedrons and truncated-cubes were prepared in a facile way. Furthermore, first principle calculation based on density functional theory was carried out to calculate the adsorption energies of OH- on different crystal planes of Fe3O4. The calculation results interpreted the crystal morphology changes accordingly, despite of the simplicity of the calculation model. The agreement between the theoretical calculation and the experimental data indicates the promising benefit of using first principle calculation to predict and design crystal morphologies in the future. On the other hand, size of the anisotropic octahedral Fe3O4 nanoparticles could be regulated from 30 nm to 115 nm by changing the volume ratio of EG/DEG with a certain OH- concentration.

中文翻译：

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第一性原理计算支持的OH-浓度对Fe3O4纳米颗粒形貌的影响

摘要 众所周知，形貌和尺寸会影响结晶磁铁矿（Fe3O4）的性质。然而，仍然缺乏一种简单且可预测的方法来控制它们的具体原则。碱浓度已被证明是乙二醇/二甘醇 (EG/DEG) 二元溶剂热系统中形态变化的影响因素。在这项工作中，以简单的方式制备了具有各种形态的晶体 Fe3O4 纳米粒子，包括簇、实心球、八面体、截八面体、十四面体和截立方。此外，进行了基于密度泛函理论的第一原理计算，计算了 OH- 在 Fe3O4 不同晶面上的吸附能。计算结果解释了晶体形貌的相应变化，尽管计算模型简单。理论计算与实验数据之间的一致性表明，使用第一性原理计算来预测和设计晶体形态在未来具有广阔的前景。另一方面，通过在一定的 OH-浓度下改变 EG/DEG 的体积比，可以将各向异性八面体 Fe3O4 纳米粒子的尺寸从 30 nm 调节到 115 nm。