Evidence for superionic H2O and diffusive He-H2O at high temperature and high pressure
Evidence for superionic H2O and diffusive He-H2O at high temperature and high pressure
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高温高压下超离子 H2O 和扩散 He-H2O 的证据
DOI：
10.1088/1361-648x/ac8134
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Yoo Choong-Shik
中科院分区：
文献类型：
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作者：
Kim Minseob;Oka Kenta;Ahmed Sohan;Somayazulu Maddury S;Meng Yue;Yoo Choong-Shik
基于斜激光加热样品的时间分辨x射线衍射实验，我们首次提出了在h2o中形成超离子相的证据，并首次发现了扩散的h2o -he相。衍射结果表明，超离子h2o和扩散的he - h2o具有相似的bcc类结构，但具有不同的跃迁动力学。根据晶格参数的时间和温度演化，在1350 ~ 1400k的23gpa温度范围内，纯h2o中超离子h2o相逐渐形成，而在1300k的26gpa温度范围内，扩散的he - h2o相突然形成。我们认为He - h2o中更快的动力学和更低的转变温度是由于空隙填充的He原子比更强结合的H原子具有更大的扩散系数。这一猜想与在较低温度下预测的He无序扩散相一致，而不是He - h2o中的h无序超离子相。
We present the evidence of superionic phase formed in H 2 O and, for the first time, diffusive H 2 O–He phase, based on time-resolved x-ray diffraction experiments performed on ramp-laser-heated samples in diamond anvil cells. The diffraction results signify a similar bcc-like structure of superionic H 2 O and diffusive He–H 2 O, while following different transition dynamics. Based on time and temperature evolution of the lattice parameter, the superionic H 2 O phase forms gradually in pure H 2 O over the temperature range of 1350–1400 K at 23 GPa, but the diffusive He–H 2 O phase forms abruptly at 1300 K at 26 GPa. We suggest that the faster dynamics and lower transition temperature in He–H 2 O are due to a larger diffusion coefficient of interstitial-filled He than that of more strongly bound H atoms. This conjecture is then consistent with He disordered diffusive phase predicted at lower temperatures, rather than H-disordered superionic phase in He–H 2 O.