Zhu Sheng-Cai, Chen Gu-Wen, Zhang Dongzhou, Xu Liang, Liu Zhi-Pan, Mao Ho-Kwang, Hu Qingyang
School of Materials, Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China.
Hawai'i Institute of Geophysics and Planetology, School of Ocean Earth Science and Technology, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States.
J Am Chem Soc. 2022 Apr 27;144(16):7414-7421. doi: 10.1021/jacs.2c01717. Epub 2022 Apr 14.
Identifying ordering in non-crystalline solids has been a focus of natural science since the publication of Zachariasen's random network theory in 1932, but it still remains as a great challenge of the century. Literature shows that the hierarchical structures, from the short-range order of first-shell polyhedra to the long-range order of translational periodicity, may survive after amorphization. Here, in a piece of AlPO, or berlinite, we combine X-ray diffraction and stochastic free-energy surface simulations to study its phase transition and structural ordering under pressure. From reversible single crystals to amorphous transitions, we now present an unambiguous view of the topological ordering in the amorphous phase, consisting of a swarm of Carpenter low-symmetry phases with the same topological linkage, trapped in a metastable intermediate stage. We propose that the remaining topological ordering is the origin of the switchable "memory glass" effect. Such topological ordering may hide in many amorphous materials through disordered short atomic displacements.
自1932年扎卡里亚森的随机网络理论发表以来，确定非晶态固体中的有序性一直是自然科学的一个焦点，但它仍然是本世纪的一个巨大挑战。文献表明，从第一壳层多面体的短程有序到平移周期性的长程有序，层次结构在非晶化后可能仍然存在。在这里，在一块磷酸铝（或水合硅铝石）中，我们结合X射线衍射和随机自由能表面模拟来研究其在压力下的相变和结构有序性。从可逆的单晶到非晶转变，我们现在展示了非晶相中拓扑有序性的明确视图，它由一群具有相同拓扑连接的卡彭特低对称相组成，被困在一个亚稳中间阶段。我们提出，剩余的拓扑有序性是可切换“记忆玻璃”效应的起源。这种拓扑有序性可能通过无序的短原子位移隐藏在许多非晶材料中。
