Detection of first-order liquid/liquid phase transitions in yttrium oxide-aluminum oxide melts
Detection of first-order liquid/liquid phase transitions in yttrium oxide-aluminum oxide melts
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DOI：
10.1126/science.1160766
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发表时间：
2008-10-24
期刊：
影响因子：
56.9
通讯作者：
Hennet, L.
中科院分区：
文献类型：
--
作者：
Greaves, G. N.;Wilding, M. C.;Hennet, L.
我们结合联合收割机小角X射线散射（SAXS）和广角X射线散射（WAXS）与空气动力学悬浮技术，研究在非接触条件下的液态原位相变。在非常高的温度下，氧化钇-氧化铝熔体显示出一级转变，这是先前从淬火玻璃中的相分离推断的。我们展示了如何过渡符合一个狭窄的和可逆的最大SAXS指示的液体在纳米尺度上的不混合，结合在原子尺度上的多面体包装的可逆变化相关的WAXS功能的突然重新排列。我们还观察到悬浮过冷液滴中由重复跃迁驱动的旋转作用（多晶转子），由此可以估计摩尔体积（1.2 +/- 0.2立方厘米）和熵（19 +/- 4焦耳摩尔（-1）开尔文（-1））的可逆变化。
We combine small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) with aerodynamic levitation techniques to study in situ phase transitions in the liquid state under contactless conditions. At very high temperatures, yttria-alumina melts show a first-order transition, previously inferred from phase separation in quenched glasses. We show how the transition coincides with a narrow and reversible maximum in SAXS indicative of liquid unmixing on the nanoscale, combined with an abrupt realignment in WAXS features related to reversible shifts in polyhedral packing on the atomic scale. We also observed a rotary action in the suspended supercooled drop driven by repetitive transitions (a polyamorphic rotor) from which the reversible changes in molar volume (1.2 +/- 0.2 cubic centimeters) and entropy (19 +/- 4 joules mole(-1) kelvin(-1)) can be estimated.