发表机构
Max Planck Institute for Sustainable Materials; Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University; Department of Materials Science and Engineering, Delft University of Technology（马克斯·普朗克可持续材料研究所; 西安交通大学; 代尔夫特理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出位错连接作为磁铁矿与赤铁矿相变的基本缺陷，通过拓扑模型预测、实验验证和原子模拟，揭示了相界面传播机制，与实验观察高度一致。
AI 中文摘要
尽管金属氧化物体系的氧化还原反应受到广泛关注，但对磁铁矿（${\ m Fe_3 O_4}$）与赤铁矿（${\ m Fe_2 O_3}$）之间相变的原子级详细理解仍然缺乏。磁铁矿到赤铁矿的转变涉及向体系中添加氧，因此产生净扩散通量，但据报道，赤铁矿会沿密排的$\{0001\}_{\ m Fe_2 O_3}//\{111\}_{\ m Fe_3 O_4}$平面上的明确惯习面生长。因此，块体中相界面的传播被认为在剪切作用下保持氧亚晶格固定，并需要铁离子的长程扩散。在本信中，我们提出具有位错特征的界面台阶，即位错连接，作为传播该转变的基本缺陷。我们利用界面缺陷的拓扑模型预测了该体系的三种位错连接模式，并采用扫描透射电子显微镜确认了它们在部分氧化磁铁矿粉末的赤铁矿/磁铁矿界面中的存在。利用原子模拟，我们确定了位错连接的平衡结构，并研究了它们的运动以及它们如何完成转变，与原子分辨率的实验观察取得了极好的一致性。
英文摘要
Detailed atomic-level understanding of the phase transformation between magnetite (${\rm Fe_3 O_4}$) and haematite (${\rm Fe_2 O_3}$) is lacking, despite widespread interest in redox reactions of metal oxide systems. While the magnetite-to-haematite transformation entails the addition of oxygen to the system and thus a net diffusive flux, haematite formations have been reported to grow along well-defined habits on the close-packed $\{0001\}_{\rm Fe_2 O_3}//\{111\}_{\rm Fe_3 O_4}$ planes. The propagation of the phase interface in the bulk is thus thought to maintain the oxygen sublattice fixed up to a shear, and to require long-range diffusion of iron ions. In this letter we propose interfacial steps with dislocation character, i.e. disconnections, as the elementary defects propagating the transformation. We use the topological model of interfacial defects to predict three disconnection modes for the system, and we employ scanning transmission electron microscopy to ascertain their presence in a haematite/magnetite interface of a partially oxidised magnetite powder. Using atomistic simulations, we determine the equilibrium structures of the disconnections, and study their motion and how they accomplish the transformation, obtaining excellent agreement with atomic-resolution experimental observations.
Comments7 pages and 4 figures in the main text; 10 pages and 6 figures in supporting information
