Time-resolved x-ray diffraction across water-ice-VI/VII transformations using the dynamic-DAC

Jing-Yin Chen,Choong-Shik Yoo,Minseob Kim,William J Evans,Hanns-Peter Liermann

doi:10.1088/1742-6596/500/14/142006

Abstract

We present recent time-resolved x-ray diffraction data obtained across the solidification of water to ice-VI and -VII at different compression rates. The structural evolution of ice-VI to ice-VII, however, is not a sharp transition, but occurs rather coarsely. The diffraction data shows an anisotropic compression behavior for ice VI; that is, the c-axis is more compressible than the a-axis at the same compression rate. Nevertheless, the present equations of state of both ice-VI and ice-VII obtained under dynamic loadings agree well with those previously obtained under static conditions. Hence, the present study demonstrates that time-resolved x-ray diffraction coupled with the dynamic-DAC is an effective method for investigating details of the structural response of materials over a wide range of well-controlled compression rates. Finally, we found the evidence for an X-ray induced chemical reaction of water and ice-VI. The impurities, produced by the x-ray induced chemical reaction, inhibit the formation of amorphous ice.

Highlights

IntroductionThe phase diagram of water (figure 1) exhibits a large number of polymorphs with a great diversity of crystalline structure, chemical bonding, and collective interactions [1,2,3]
Abundant in nature, water is a major constituent of planets and living organisms
We report time-resolved xray diffraction data probing the structural evolution associated with the solidification of water to ice-VI and ice-VII

Summary

Introduction

The phase diagram of water (figure 1) exhibits a large number of polymorphs with a great diversity of crystalline structure, chemical bonding, and collective interactions [1,2,3]. In addition to the fifteen known solid phases of H2O, there are many metastable phases These include several metastable phases of ice-IV near the melt line [4] and metastable ice-VII in the stability field of ice-VI [5], highand low-density amorphous ice (HDA and LDA) at low temperatures [6,7,8,9,10,11], and high- and low-density water (HDW and LDW) [12]. Liquid water under dynamic conditions is observed beyond the equilibrium liquid-solid phase transition boundaries. The stability limit conjecture of liquid water [2], shown as the green curve, is estimated from the homogeneous nucleation temperatures of the super-cooled liquid

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