Very sharp diffraction peak in nonglass-forming liquid with the formation of distorted tetraclusters

Chihiro Koyama, Shuta Tahara, Shinji Kohara, Yohei Onodera, Didrik R. Småbråten, Sverre M. Selbach, Jaakko Akola, Takehiko Ishikawa, Atsunobu Masuno, Akitoshi Mizuno, Junpei T. Okada, Yuki Watanabe, Yui Nakata, Koji Ohara, Haruka Tamaru, Hirohisa Oda, Ippei Obayashi, Yasuyuki Hiraoka, Osami Sakata

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Understanding the liquid structure provides information that is crucial to uncovering the nature of the glass-liquid transition. We apply an aerodynamic levitation technique and high-energy X-rays to liquid (l)-Er2O3 to discover its structure. The sample densities are measured by electrostatic levitation at the International Space Station. Liquid Er2O3 displays a very sharp diffraction peak (principal peak). Applying a combined reverse Monte Carlo – molecular dynamics approach, the simulations produce an Er–O coordination number of 6.1, which is comparable to that of another nonglass-forming liquid, l-ZrO2. The atomic structure of l-Er2O3 comprises distorted OEr4 tetraclusters in nearly linear arrangements, as manifested by a prominent peak observed at ~180° in the Er–O–Er bond angle distribution. This structural feature gives rise to long periodicity corresponding to the sharp principal peak in the X-ray diffraction data. A persistent homology analysis suggests that l-Er2O3 is homologically similar to the crystalline phase. Moreover, electronic structure calculations show that l-Er2O3 has a modest band gap of 0.6 eV that is significantly reduced from the crystalline phase due to the tetracluster distortions. The estimated viscosity is very low above the melting point for l-ZrO2, and the material can be described as an extremely fragile liquid.

Original languageEnglish
Article number43
JournalNPG Asia Materials
Issue number1
Publication statusPublished - 2020 Dec 1


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