Masuno Atsunobu, Koyama Chihiro, Kohara Shinji, Sasaki Shunta, Izumi Satoshi, Matsuya Tomoharu, Mikami Yuki, Yoshida Kenta, Kobayashi Hirotaka, Watanabe Yuki, Mizuno Akitoshi, Oda Hirohisa, Shuseki Yuta, Watanabe Manabu, Okada Junpei T, Ishikawa Takehiko
Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo-ku, Kyoto, 615-8520, Japan.
Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori, 036-8505, Japan.
NPJ Microgravity. 2025 Aug 25;11(1):58. doi: 10.1038/s41526-025-00520-w.
The LaO-NbO binary system is a unique glass-forming system without conventional network former oxides, exhibiting two distinct glass-forming regions: LaO-rich and NbO-rich compositions. To evaluate its glass-forming ability, the temperature dependence of density, viscosity, and surface tension was measured using the electrostatic levitation furnace aboard the International Space Station (ISS-ELF). Melt density showed linear temperature dependence, and thermal expansion coefficients at 2000 K varied from 2.5 × 10 to 4.0 × 10 K. Substantial undercooling was observed for glass-forming compositions. Viscosity measurements above the melting point revealed that both LaO-rich and NbO-rich melts behave as fragile liquids. Activation energy derived from viscosity data was higher for glass-forming compositions. These results suggest that glass-forming ability can be assessed based on undercooling and activation energy across a wide compositional range, including non-glass-forming melts. The ISS-ELF experiments provide a valuable platform for understanding glass formation in systems inaccessible by terrestrial techniques.
LaO-NbO二元体系是一个独特的玻璃形成体系，其中没有传统的网络形成氧化物，呈现出两个不同的玻璃形成区域：富LaO和富NbO的成分。为了评估其玻璃形成能力，利用国际空间站上的静电悬浮炉（ISS-ELF）测量了密度、粘度和表面张力的温度依赖性。熔体密度呈现出线性温度依赖性，在2000 K时的热膨胀系数在2.5×10至4.0×10 K之间变化。对于玻璃形成成分观察到了显著的过冷现象。在熔点以上的粘度测量表明，富LaO和富NbO的熔体均表现为脆性液体。从粘度数据得出的玻璃形成成分的活化能更高。这些结果表明，可以基于过冷和活化能在包括非玻璃形成熔体在内的广泛成分范围内评估玻璃形成能力。ISS-ELF实验为理解地面技术无法触及的体系中的玻璃形成提供了一个有价值的平台。
