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In the Crystal Physics Lab, we mainly research quasicrystals.
In the Crystal Physics Lab, we mainly research quasicrystals.
Qasicrystals
Qasicrystals
Quasicrystals were discovered in 1984 by Shechtman (Nobel Prize in Chemistry 2011) in rapidly cooled AlMn alloys, exhibiting a 5-fold symmetric electron diffraction pattern. Since crystals demonstrating 5-fold symmetry were traditionally thought not to exist, this discovery was initially met with significant surprise and skepticism. However, it became evident that this alloy is composed of atoms arranged in a regular pattern similar to crystals. This ordered arrangement is referred to as quasiperiodicity, and materials with such quasi-periodicity and regularly arranged atoms are termed quasicrystals. Quasicrystals, found not only in metallic systems but also in polymer and ceramic systems, exhibit rotational symmetries such as 5-fold, 8-fold, 10-fold, and 12-fold that are not permitted in periodic crystals. They are also associated with irrational numbers like the golden ratio and fractals (self-similarity). Since quasicrystals lack periodicity unlike conventional crystals, understanding how atoms are orderly arranged in their structure has been a major challenge since their discovery. Elucidating the atomic-level structure of materials forms the foundation of modern materials science. Additionally, it is crucial to understand how the properties (physical characteristics) of materials differ from those of crystals with periodicity and amorphous (non-crystalline) materials. In our research laboratory, we primarily investigate the structure and properties of alloy-based quasicrystals.Ā
Keywords: Crystal Physics, Crystallography, Structure and Properties of Quasicrystals, Complex Alloy Crystal Structures, Analysis of Non-periodic Crystal Structures, Metal Magnetism and Electron Transport
ć»Structure of quasicrystals
ć»Structure of quasicrystals
The atomic arrangement in quasicrystals remains poorly understood despite the discovery of numerous quasicrystals to date. In our research laboratory, we contributed to Shechtman's Nobel Prize by elucidating the structure of the Yb-Cd icosahedral quasicrystal, the first quasicrystal composed of two elements. This structure model serves as a foundational basis for understanding the structure and properties of multicomponent Tsai-type quasicrystals, which are currently actively researched. We are advancing high-dimensional crystallography to tackle the elucidation of unknown structures.
The structure of the Yb-Cd icosahedral quasicrystalĀ
ć»Physical properties of quasicrystals
ć»Physical properties of quasicrystals
When atoms are arranged in a quasiperiodic manner, unique properties emerge, one of which is quantum criticality. Additionally, understanding how atoms bond in quasicrystals is intriguing. For example, the AlCuFe icosahedral quasicrystal, composed of common metallic elements, exhibits unusual characteristics such as hardness and brittleness, breaking upon impact. This metal-to-semiconductor transition in quasicrystals represents a promising new direction for material design.
Furthermore, the electronic states in quasiperiodic structures differ from those in periodic systems. Many aspects of these behaviors remain unexplored.
The temperature dependence of the magnetization susceptibility in Au-Al-Yb quasicrystals
Previous academic thesis
Previous academic thesis
ć»2024
Masterļ¼Kodai Mizunumać
Masterļ¼Satoshi Mizutanić
Bachelorļ¼Heizo Kawaharada
Bachelorļ¼Tenshin Seki
Bachelorļ¼Yugo Hayasaka
Bachelorļ¼Hayato Konno
ć»2023
Masterļ¼Hiroki Satoć"Zn-Ag-Sc-(Rare Earth) Quasicrystals and Approximant Structures: Rare Earth Substitution Limits and Low-Temperature Properties"
Bachelor ļ¼Yoshiki Saitoć"Development of Quasicrystal-Related Crystals in Al-Ir-TM (TM=Mn, Fe) Systems and Their Structures"
ć»2022
Masterļ¼Ryota Kikuchić"Structures of 3/2-2/1-2/1 Approximant Quasicrystals in the Mg-Al-Ga-Zn System"
Bachelorļ¼Kodai Mizunumać"Cluster Structure of F-type Icosahedral Quasicrystals in the Al-Cu-Fe System"
Bachelorļ¼Satoshi Mizutanić"Structural Distortion of Bergman-type AlZnMg 2/1 Approximant Quasicrystals"
Bachelorļ¼Keita Matushitać"Rare Earth Substitution Effects on Phase Formation and Properties in Cu-Ga-based Tsai-type Quasicrystals and Approximants"
ć»2021
Masterļ¼Takahito Endoć"Formation and Structure of Icosahedral Quasicrystals in the Zn-Mg-Zr System"
Bachelorļ¼Hiroki Satoć"Sample Evaluation and Isomorphic Substitution Limits of Icosahedral Quasicrystals in the Zn-Ag-(Sc-lanthanoid) System"
Bachelorļ¼Yuta Konoć"Formation and Phase Stability of Tsai-type Icosahedral Quasicrystals in Zn-Mg-Sc-Er Alloy Systems"
Bachelorļ¼Kazuki Takahashić"Structural Changes Depending on Composition in Tsai-type Zn-Sc 1/1 Approximant Quasicrystals"
Bachelorļ¼Takamasa Mitsutać"Structure Analysis of Cubic Crystals with Giant Unit Cells in the Zn-Mg-Ti System"
ć»2020
Masterļ¼Ryosei Shibatać"Growth and Structure Determination of Single Crystals of Approximant Quasicrystals in Al-Si-Ru Systems (Cubic and Orthorhombic)"
Bachelorļ¼Ryota Kikuchić"Exploration of Formation Conditions for 2/1-1/1-1/1 Approximant Quasicrystals in Al-Zn-Mg Systems"
Bachelorļ¼Tatsuya Yamashitać"Single Crystal X-ray Structure Analysis of 1/1 Approximant Quasicrystals in Au-In-Eu and 2/1 Approximant Quasicrystals in Au-Sn-Eu"
(Note: Years before 2020 are omitted.)
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