Publications by authors named "Junpei T Okada"

Article Synopsis
  • Understanding disordered structures in materials is challenging due to limited experimental data, but this study combines diffraction and simulations to analyze oxygen packing and network topology in various MgO-SiO systems.
  • The research reveals that oxygen packing is larger in glass forms than in liquid forms, and suggests that the similarity in topology between certain crystalline and glass forms indicates low glass-forming ability (GFA), whereas unique topologies correspond to high GFA.
  • It concludes that the GFA of MgO-SiO is primarily influenced by atomic structure and network topology, rather than electronic structure.
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Because ice surfaces catalyze various key chemical reactions impacting nature and human life, the structure and dynamics of interfacial layers between water vapor and ice have been extensively debated with attention to the quasi-liquid layer. Other interfaces between liquid water and ice remain relatively underexplored, despite their importance and abundance on the Earth and icy extraterrestrial bodies. By in situ optical microscopy, we found that a high-density liquid layer, distinguishable from bulk water, formed at the interface between water and high-pressure ice III or VI, when they were grown or melted in a sapphire anvil cell.

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The structure of high-temperature liquids is an important topic for understanding the fragility of liquids. Here we report the structure of a high-temperature non-glass-forming oxide liquid, ZrO2, at an atomistic and electronic level. The Bhatia-Thornton number-number structure factor of ZrO2 does not show a first sharp diffraction peak.

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A compact electrostatic levitator was developed for the structural analysis of high-temperature liquids by x-ray diffraction methods. The size of the levitator was 200 mm in diameter and 200 mm in height and can be set up on a two axis diffractometer with a laboratory x-ray source, which is very convenient in performing structural measurements of high-temperature liquids. In particular, since the laboratory x-ray source allows a great amount of user time, preliminary or challenging experiments can be performed with trial and error, which prepares and complements synchrotron x-ray experiments.

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