Pressure-induced polyamorphic transition in CaA l 2 O 4 glass

作者：Itaru Ohira, Yoshio Kono, Steeve Gréaux, James W. E. Drewitt, Sandro Jahn, Fumiya Noritake, Koji Ohara, Satoshi Hiroi, Nozomi Kondo, Rostislav Hrubiak, Yuji Higo, Noriyoshi Tsujino, Sho Kakizawa, Kiyofumi Nitta, Oki Sekizawa · 发表于：Physical review. B./Physical review. B · 年份：2024 · DOI：10.1103/physrevb.110.054115 · 被引用次数：5 · 研究领域：Glass properties and applications、Luminescence Properties of Advanced Materials、Material Dynamics and Properties

In situ high-pressure ultrasonic velocity measurements of $\mathrm{CaA}{\mathrm{l}}_{2}{\mathrm{O}}_{4}$ glass reveal abrupt irreversible discontinuities in the elastic wave velocities at \ensuremath{\sim}8--10 GPa. Total structure factor and pair distribution functions measured by synchrotron x-ray diffraction show a rapid change in the intermediate range structure attributed to a rearrangement of calcium ions over this narrow pressure region. Atomistic models obtained from molecular dynamics simulations reveal that this intermediate range structure is explained by a transition of Ca--O void radius distribution from a bimodal distribution with peaks at \ensuremath{\sim}2.1 and \ensuremath{\sim}2.4 \AA{} to a single distribution centered at \ensuremath{\sim}2.1 \AA{}. These abrupt structural changes involving the rapid increase in elastic wave velocity are markedly different to the continuous transformations observed in conventional network-forming glasses, such as $\mathrm{Si}{\mathrm{O}}_{2}$.