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Nanosecond X-ray diffraction of shock-compressed superionic water ice

机译：冲击压缩超离子水冰的纳秒X射线衍射

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Since Bridgman's discovery of five solid water (H2O) ice phases(1) in 1912, studies on the extraordinary polymorphism of H2O have documented more than seventeen crystalline and several amorphous ice structures(2,3), as well as rich metastability and kinetic effects(4,5). This unique behaviour is due in part to the geometrical frustration of the weak intermolecular hydrogen bonds and the sizeable quantum motion of the light hydrogen ions (protons). Particularly intriguing is the prediction that H2O becomes superionic(6-12)-with liquid-like protons diffusing through the solid lattice of oxygen- when subjected to extreme pressures exceeding 100 gigapascals and high temperatures above 2,000 kelvin. Numerical simulations suggest that the characteristic diffusion of the protons through the empty sites of the oxygen solid lattice (1) gives rise to a surprisingly high ionic conductivity above 100 Siemens per centimetre, that is, almost as high as typical metallic (electronic) conductivity, (2) greatly increases the ice melting temperature(7-13) to several thousand kelvin, and (3) favours new ice structures with a close-packed oxygen lattice(13-15). Because confining such hot and dense H2O in the laboratory is extremely challenging, experimental data are scarce. Recent optical measurements along the Hugoniot curve (locus of shock states) of water ice VII showed evidence of superionic conduction and thermodynamic signatures for melting(16), but did not confirm the microscopic structure of superionic ice. Here we use laser-driven shockwaves to simultaneously compress and heat liquid water samples to 100-400 gigapascals and 2,000-3,000 kelvin. In situ X-ray diffraction measurements show that under these conditions, water solidifies within a few nanoseconds into nanometre-sized ice grains that exhibit unambiguous evidence for the crystalline oxygen lattice of superionic water ice. The X-ray diffraction data also allow us to document the compressibility of ice at these extreme conditions and a temperature- and pressure induced phase transformation from a body-centred-cubic ice phase (probably ice X) to a novel face-centred-cubic, superionic ice phase, which we name ice XVIII2,17.
机译：自从布里奇曼（Bridgman）在1912年发现五个冰水相（1）以来，关于水的非同寻常多态性的研究已经证明了十七种以上的结晶和几种无定形冰结构（2,3），以及丰富的亚稳性和动力学效应（4,5）。这种独特的行为部分归因于弱分子间氢键的几何结构受阻以及轻氢离子（质子）的相当大的量子运动。尤其令人着迷的是，当承受超过100吉帕的极端压力和2,000开尔文以上的高温时，H2O会变成超离子型（6-12）-液态质子扩散穿过氧气的固态晶格。数值模拟表明，质子通过氧固态晶格（1）的空位的特征扩散会导致令人惊讶的高离子电导率，高于100西门子/厘米，即几乎与典型的金属（电子）电导率一样高， （2）大大提高了冰的融化温度（7-13）至数千开尔文，（3）倾向于采用密排氧晶格的新型冰结构（13-15）。由于在实验室中限制这种热和浓的H2O极具挑战性，因此缺乏实验数据。最近沿水冰VII的Hugoniot曲线（冲击状态的位点）进行的光学测量显示出超离子传导和融化的热力学特征的证据（16），但没有证实超离子冰的微观结构。在这里，我们使用激光驱动的冲击波将液态水样本同时压缩和加热到100-400吉帕斯卡和2,000-3,000开尔文。原位X射线衍射测量表明，在这些条件下，水在几纳秒内凝固成纳米级的冰粒，这些冰粒显示出超离子水冰晶态氧晶格的明确证据。 X射线衍射数据还允许我们记录在这些极端条件下冰的可压缩性，以及温度和压力引起的从体心立方冰相（可能是冰X）到新型面心立方的相变。 ，超离子冰相，我们将其命名为冰XVIII2,17。

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  • 来源
    《Nature》 |2019年第7755期|251-255|共5页
  • 作者

    Millot Marius; Coppari Federica; Rygg J. Ryan; Barrios Antonio Correa; Hamel Sebastien; Swift Damian C.; Eggert Jon H.;

  • 作者单位

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA|Univ Rochester, Laser Energet Lab, Rochester, NY USA|Univ Rochester, Dept Mech Engn, Rochester, NY 14627 USA;

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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