Pressure-induced reversal of Peierls-like distortions elicits the polyamorphic transition in GeTe and GeSe

• Published in: Nature communications Vol. 14; no. 1; p. 7851
• Main Authors: Fujita, Tomoki, Chen, Yuhan, Kono, Yoshio, Takahashi, Seiya, Kasai, Hidetaka, Campi, Davide, Bernasconi, Marco, Ohara, Koji, Yumoto, Hirokatsu, Koyama, Takahisa, Yamazaki, Hiroshi, Senba, Yasunori, Ohashi, Haruhiko, Inoue, Ichiro, Hayashi, Yujiro, Yabashi, Makina, Nishibori, Eiji, Mazzarello, Riccardo, Wei, Shuai
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07.12.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/301/119/1002; 639/766/25; Amorphous materials; Atomic structure; Coherence length; Compressibility; Crystallization; Distortion; Distribution functions; Energy; High pressure; Humanities and Social Sciences; Liquid phases; multidisciplinary; Neural networks; Phase change materials; Polymorphism; Pressure; Science; Science (multidisciplinary); Simulation; Structural analysis; Supercooling; Synchrotron radiation; Synchrotrons; Vitrification; X-rays
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-43457-y

While polymorphism is prevalent in crystalline solids, polyamorphism draws increasing interest in various types of amorphous solids. Recent studies suggested that supercooling of liquid phase-change materials (PCMs) induces Peierls-like distortions in their local structures, underlying their liquid-liquid transitions before vitrification. However, the mechanism of how the vitrified phases undergo a possible polyamorphic transition remains elusive. Here, using high-energy synchrotron X-rays, we can access the precise pair distribution functions under high pressure and provide clear evidence that pressure can reverse the Peierls-like distortions, eliciting a polyamorphic transition in GeTe and GeSe. Combined with simulations based on machine-learned-neural-network potential, our structural analysis reveals a high-pressure state characterized by diminished Peierls-like distortion, greater coherence length, reduced compressibility, and a narrowing bandgap. Our finding underscores the crucial role of Peierls-like distortions in amorphous octahedral systems including PCMs. These distortions can be controlled through pressure and composition, offering potentials for designing properties in PCM-based devices. The subtle distortion in atomic structure underlies the drastic changes in the properties of amorphous phase-change materials. Here authors show that that pressure can reverse the Peierls-like distortions introduced by temperature, eliciting a polyamorphic transition in GeTe and GeSe.