AI 中文总结
研究通过建立二维相场模型，探讨TiO2纳米雕刻中形态演变，纳入多种因素，经模拟明确各向异性因素作用，确定反应速率各向异性为主导，还探索晶粒取向差角影响，为微观结构演变及控制提供见解和指导。
AI 中文摘要
TiO2纳米晶体可通过用还原性含氢气体雕刻TiO2块状多晶体来制备，得到单晶[001]纳米线阵列。然而，纳米雕刻过程中强各向异性纳米线形态的起源在很大程度上仍未得到探索。在本研究中，我们建立了一个二维相场模型来研究纳米雕刻过程中TiO2的形态演变。该模型纳入了TiO2还原反应、Ti3+扩散以及表面能、扩散率和反应速率的各向异性。通过对单晶和多晶的系统模拟，我们阐明了不同各向异性因素在不同雕刻阶段对纳米晶体形态的作用，确定强反应速率各向异性是实验观察到的纳米线形态的主导因素。我们进一步探索了晶粒取向差角的影响，生成了纳米雕刻形态图以指导晶粒取向控制。本研究为纳米雕刻过程中的微观结构演变机制提供了见解，并为相关微观结构控制提供了指导。
英文摘要
TiO2 nanocrystals can be fabricated by carving the TiO2 bulk polycrystals using reductive H2-bearing gases, yielding single-crystal [001] nanowire arrays. However, the origin of the strongly anisotropic nanowire morphology during nanocarving remains largely unexplored. In this study, we formulate a 2-D phase-field model to investigate the TiO2 morphology evolution during nanocarving processes. The model incorporates TiO2 reduction reaction, Ti3+ diffusion, and anisotropies in surface energy, diffusivity and reaction rate. Through systematic simulations in both single- and poly-crystals, we elucidate the roles of different anisotropy factors in nanocrystal morphologies at different carving stages, identifying the strong reaction rate anisotropy as the dominant factor for experimentally observed nanowire morphologies. We further explore the effect of grain misorientation angle, generating a nanocarving morphology map to guide grain orientation control. This study provides insights into microstructure evolution mechanisms during nanocarving and guidances for related microstructure control.
