Nature of Rutile Nuclei in Anatase-to-Rutile Phase Transition,Journal of the American Chemical Society

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Nature of Rutile Nuclei in Anatase-to-Rutile Phase Transition
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2015-08-26 , DOI: 10.1021/jacs.5b07734
Sheng-Cai Zhu ₁ , Song-Hai Xie ₁ , Zhi-Pan Liu ₁

Affiliation

The solid phase transition of TiO2, in particular anatase to rutile, has been extensively studied in the past 30 years. To seek the nucleation site at the beginning of phase transition is highly challenging, which asks for new theoretical techniques with high spatial and temporal resolution. This work reports the first evidence on the atomic structure of the nucleation sites in the TiO2 anatase-to-rutile phase transition. Novel automated theoretical methods, namely stochastic surface walking based pathway sampling methods, are utilized to resolve the lowest energy pathways at the initial stage of phase transition. We show that among common anatase surfaces, only the (112) ridged surface provides the nucleation site for phase transition, which can lead to the formation of both TiO2-II and brookite thin slabs. The TiO2-II phase is kinetically preferred product; the propagation into the subsurface is still hindered by high barriers that is the origin for the slow kinetics of nuclei formation. The rutile nuclei are thus not rutile phase but nascent metastable TiO2-II phase in an anatase matrix. The phase transition kinetics is found to be sensitive to the compressive strain and the crystallographic directions. The results rationalize the size and morphology dependence of the anisotropic phase transition kinetics of anatase particles and could facilitate the rational design of material via controlled solid phase transition.

中文翻译：

锐钛矿到金红石相变中金红石核的性质

TiO2 的固相转变，特别是锐钛矿到金红石的转变，在过去的 30 年中得到了广泛的研究。在相变开始时寻找成核位点是非常具有挑战性的，这需要具有高空间和时间分辨率的新理论技术。这项工作报告了关于 TiO2 锐钛矿到金红石相变中成核位点的原子结构的第一个证据。新的自动化理论方法，即基于随机表面行走的路径采样方法，用于解决相变初始阶段的最低能量路径。我们表明，在常见的锐钛矿表面中，只有 (112) 脊状表面为相变提供了成核位点，这会导致 TiO2-II 和板钛矿薄板的形成。TiO2-II 相是动力学优选的产物；进入地下的传播仍然受到高势垒的阻碍，这是核形成缓慢动力学的起源。因此，金红石晶核不是金红石相，而是锐钛矿基质中新生的亚稳态 TiO2-II 相。发现相变动力学对压缩应变和结晶方向敏感。结果合理化了锐钛矿颗粒各向异性相变动力学的尺寸和形态依赖性，并且可以通过受控的固相转变促进材料的合理设计。因此，金红石晶核不是金红石相，而是锐钛矿基质中新生的亚稳态 TiO2-II 相。发现相变动力学对压缩应变和结晶方向敏感。结果合理化了锐钛矿颗粒各向异性相变动力学的尺寸和形态依赖性，并且可以通过受控的固相转变促进材料的合理设计。因此，金红石晶核不是金红石相，而是锐钛矿基质中新生的亚稳态 TiO2-II 相。发现相变动力学对压缩应变和结晶方向敏感。结果合理化了锐钛矿颗粒各向异性相变动力学的尺寸和形态依赖性，并且可以通过受控的固相转变促进材料的合理设计。

更新日期：2015-08-26

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