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 (+7 others)
2020 NPG Asia Materials  
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)-Er 2 O 3 to discover its structure. The sample densities are measured by electrostatic levitation at the International Space Station. Liquid Er 2 O 3 displays a very sharp diffraction peak (principal peak). Applying a combined reverse Monte Carlomolecular dynamics approach, the
more » ... oach, the simulations produce an Er-O coordination number of 6.1, which is comparable to that of another nonglass-forming liquid, l-ZrO 2 . The atomic structure of l-Er 2 O 3 comprises distorted OEr 4 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-Er 2 O 3 is homologically similar to the crystalline phase. Moreover, electronic structure calculations show that l-Er 2 O 3 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-ZrO 2 , and the material can be described as an extremely fragile liquid.
doi:10.1038/s41427-020-0220-0 fatcat:a5v4mahucjcxfk65j6wkwpnimm