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Title: A continuum of amorphous ices between low-density and high-density amorphous ice
Abstract Amorphous ices are usually classified as belonging to low-density or high-density amorphous ice (LDA and HDA) with densitiesρLDA ≈ 0.94 g/cm3andρHDA ≈ 1.15−1.17 g/cm3. However, a recent experiment crushing hexagonal ice (ball-milling) produced amedium-density amorphous ice (MDA,ρMDA ≈ 1.06 g/cm3) adding complexity to our understanding of amorphous ice and the phase diagram of supercooled water. Motivated by the discovery of MDA, we perform computer simulations where amorphous ices are produced by isobaric cooling and isothermal compression/decompression. Our results show that, depending on the pressure employed, isobaric cooling can generate a continuum of amorphous ices with densities that expand in between those of LDA and HDA (briefly, intermediate amorphous ices, IA). In particular, the IA generated atP ≈ 125 MPa has a remarkably similar density and average structure as MDA, implying that MDA is not unique. Using the potential energy landscape formalism, we provide an intuitive qualitative understanding of the nature of LDA, HDA, and the IA generated at different pressures. In this view, LDA and HDA occupy specific and well-separated regions of the PEL; the IA prepared atP = 125 MPa is located in the intermediate region of the PEL that separates LDA and HDA.  more » « less
Award ID(s):
2329339 2223461 2112550
PAR ID:
10524819
Author(s) / Creator(s):
; ;
Publisher / Repository:
Nature Portfolio
Date Published:
Journal Name:
Communications Chemistry
Volume:
7
Issue:
1
ISSN:
2399-3669
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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