Aperiodic crystals: structure, dynamics and electronic properties

非周期晶体：结构、动力学和电子特性

• 批准号: 406658237
• 负责人: Professor Dr. Michael Engel
• 金额: --
• 依托单位: Lehrstuhl für Multiscale Simulation of Particulate Systems (MSS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/406658237?language=en
• 关键词: Aperiodic; crystals; structure; dynamics; electronic

Aperiodic crystals are materials that possess long-range order but lack lattice periodicity. They comprise incommensurately modulated structures, incommensurate composite crystals and quasicrystals. They are found in a large variety of systems, ranging from the elements to proteins. Although progress has been made in understanding their fascinating structures, the impact of aperiodic order on physical properties is still largely unexplored. The objective of the project is to provide a comprehensive understanding of the relationship between the aperiodic long-range order and physical properties, in particular the interrelation between phonon, phason, and electronic degrees of freedom. Indeed phason modes are diffusive-like excitations that are characteristic of aperiodic order, but whose interrelation with lattice dynamics and electronic properties is still not well understood. To go beyond the existing understanding, a joint effort is needed as proposed here. Six leading teams with complementary experimental and theoretical expertise in the field of aperiodic systems will together focus on the three aspects atomic structure, dynamics and phason modes, as well as electronic properties. Through a study of five well-chosen systems out of the different families of aperiodic systems, we aim at a generalized understanding of aperiodic order. We will employ the new possibilities of large-scale facilities and supplement the experimental study by state of the art atomic scale simulations, using either the DFT approach or model Hamiltonians. The specific systems are: (i) The phosphate tungsten bronzes that form two-dimensional CDW systems with soft phonon modes and phason excitations; (ii) Rb2ZnCl4 as an example of an incommensurately modulated phase, in which, for the first time, phason modes can be studied when the modulation goes from harmonic to strongly anharmonic; (iii) the incommensurate composite crystals [Sr]1+x[TiS3], exhibiting high structural order; (iv) recently discovered two-dimensional dodecagonal oxide quasicrystals, where phason flips can be atomically resolved; and (v) the Tsai-type binary icosahedral quasicrystal family. This ambitious project will gather the competences of three French and three German expert teams. Six PhDs working in close collaboration will tackle this challenging problem. The exchange of PhD students, the joint experiments, and the close cooperation with theory and structure simulations among six French-German expert teams will allow for a coherent approach and ensures broad expertise covering all aspects of aperiodic crystals. It will shine new light on aperiodic crystals and their specific properties that might pave the way also for new applications in fields such as ionic conduction, high-Tc superconductors, electronic and thermal transport, and thermoelectric materials.

非周期晶体是具有长程有序但缺乏晶格周期性的材料。它们包括无限调制结构、无公度复合晶体和准晶。它们存在于各种各样的系统中，从元素到蛋白质。虽然在理解它们迷人的结构方面已经取得了进展，但非周期性秩序对物理性质的影响仍然在很大程度上未被探索。该项目的目标是提供一个全面的理解之间的关系的非周期性长程有序和物理性质，特别是声子，相子和电子自由度之间的相互关系。事实上，相子模式是非周期性秩序的特征，但其与晶格动力学和电子性质的相互关系仍然没有得到很好的理解。为了超越现有的谅解，需要作出这里提议的共同努力。在非周期系统领域具有互补实验和理论专业知识的六个领先团队将共同关注原子结构，动力学和相子模式以及电子特性这三个方面。通过研究五个精心挑选的系统的不同家庭的非周期系统，我们的目的是在一个广义的理解非周期秩序。我们将采用大规模设施的新的可能性，并补充最先进的原子尺度模拟的实验研究，使用DFT方法或模型哈密顿。具体制度有：（i）磷酸盐钨青铜，它形成了具有软声子模和相子激发的二维CDW系统;（ii）Rb_2ZnCl_4，它作为一个非谐调制相位的例子，其中，当调制从谐波到强非谐时，第一次可以研究相子模;（iii）无公度复合晶体[Sr]_（1+x）[TiS_3]，表现出高的结构有序性;（iv）最近发现的二维十二方氧化物准晶，其中相位子翻转可以原子分辨;和（v）蔡型二元二十面体准晶家族。 这个雄心勃勃的项目将汇集三个法国和三个德国专家团队的能力。六位博士密切合作，将解决这一具有挑战性的问题。博士生的交流，联合实验，以及六个法德专家团队之间理论和结构模拟的密切合作，将允许一种连贯的方法，并确保涵盖非周期晶体各个方面的广泛专业知识。它将为非周期性晶体及其特定性质带来新的曙光，这可能为离子传导，高温超导体，电子和热传输以及热电材料等领域的新应用铺平道路。