Guiding Synthesis of Polymorphs of Materials Using Nanometric Phase Diagrams,Journal of the American Chemical Society

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Guiding Synthesis of Polymorphs of Materials Using Nanometric Phase Diagrams
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-11-13 , DOI: 10.1021/jacs.8b11029
Xuetian Ma ₁ , Adelaide M. Nolan ₂ , Shuo Zhang ₂ , Jianming Bai , Wenqian Xu ₃ , Lijun Wu , Yifei Mo ₂ , Hailong Chen ₁

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Conventionally, phase diagrams serve as road maps for the design and synthesis of materials. However, bulk phase diagrams are often not as predictive for the synthesis of nanometric materials, mainly due to the increased significance of surface energy. The change of surface energy can drastically alter the total energy of the nanocrystals and thus yields a polymorph or metastable phase different from the stable phase in bulk, providing a means for controlling the synthesis of metastable phases. To achieve a theoretical and systematical understanding on the polymorphism of nanomaterials, metallic cobalt was chosen as a model system, where the two polymorphs, fcc and hcp phases, can be tuned with 100% selectivity in a solvothermal reaction. Advanced in situ synchrotron X-ray diffraction (XRD) technique and density functional theory (DFT) calculations were complementarily employed to reveal the size- and surface-dependent polymorphism at nanometer scale. The nanometric phase diagram provides a general predictive approach to guide the synthesis of metastable materials.

中文翻译：

使用纳米相图指导材料多晶型物的合成

通常，相图用作材料设计和合成的路线图。然而，体相图通常不能预测纳米材料的合成，主要是由于表面能的重要性增加。表面能的变化可以极大地改变纳米晶体的总能量，从而产生与本体稳定相不同的多晶型物或亚稳相，为控制亚稳相的合成提供了一种手段。为了实现对纳米材料多晶型的理论和系统理解，选择金属钴作为模型系统，其中两种多晶型，fcc 和 hcp 相，可以在溶剂热反应中以 100% 的选择性进行调整。先进的原位同步加速器 X 射线衍射 (XRD) 技术和密度泛函理论 (DFT) 计算被互补地用于揭示纳米尺度上的尺寸和表面依赖性多晶型。纳米相图提供了一种通用的预测方法来指导亚稳态材料的合成。

更新日期：2018-11-13

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