ガラスの「見えない秩序」がテラヘルツ帯の揺らぎを決める

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2025-04-09 筑波大学

筑波大学を中心とする研究チームは、ガラスのテラヘルツ帯における振動特性(ボゾンピーク)が、微細な周期構造「第一鋭回折ピーク(FSDP)」に起因することを明らかにした。従来ガラスは原子が無秩序に配置された物質とされてきたが、X線・中性子線で観測されるFSDPが、材料内部の弾性の不均一性と一致することを不均一弾性体理論により示した。この発見は、ボゾンピークを制御する新しいガラス材料の開発につながる可能性がある。

<関連情報>

ガラスにおけるボゾンピークと第一鋭回折ピークの関係 Relationship between the boson peak and first sharp diffraction peak in glasses

Dan Kyotani,Soo Han Oh,Suguru Kitani,Yasuhiro Fujii,Hiroyuki Hijiya,Hideyuki Mizuno,Shinji Kohara,Akitoshi Koreeda,Atsunobu Masuno,Hitoshi Kawaji,Seiji Kojima,Yohei Yamamoto & Tatsuya Mori
Scientific Reports  Published:20 March 2025
DOI:https://doi.org/10.1038/s41598-025-94454-8

ガラスの「見えない秩序」がテラヘルツ帯の揺らぎを決める

Abstract

Boson peak (BP) dynamics refers to the universal excitation in the terahertz region of glass. In this study, the universal dynamics of BP were quantitatively evaluated in various glassy materials based on the heterogeneous elasticity theory (HET), and the determinants of BP were successfully extracted. A strong correlation was observed between the maximum possible coarse-graining wavenumber, which is a determinant of the BP in the HET, and the first sharp diffraction peak (FSDP) wavenumber, which is a characteristic index of the medium-range order in glasses. The results indicate that the behaviour of BP in glass can be quantitatively understood in the following two steps. First, the FSDP representing the largest structural correlation in glass is dominantly used to determine the unit size of the elastic modulus heterogeneity, and second, the magnitude of the elastic modulus fluctuation is used to determine the frequency and intensity of the BP.

1700応用理学一般
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