Universität zu Köln

Bykova, E., Bykov, M., Cernok, A., Tidholm, J., Simak, S. I., Hellman, O., Belov, M. P., Abrikosov, I. A., Liermann, H. -P., Hanfland, M., Prakapenka, V. B., Prescher, C., Dubrovinskaia, N. and Dubrovinsky, L. (2018). Metastable silica high pressure polymorphs as structural proxies of deep Earth silicate melts. Nat. Commun., 9. LONDON: NATURE PUBLISHING GROUP. ISSN 2041-1723

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Abstract

Modelling of processes involving deep Earth liquids requires information on their structures and compression mechanisms. However, knowledge of the local structures of silicates and silica (SiO2) melts at deep mantle conditions and of their densification mechanisms is still limited. Here we report the synthesis and characterization of metastable high-pressure silica phases, coesite-IV and coesite-V, using in situ single-crystal X-ray diffraction and ab initio simulations. Their crystal structures are drastically different from any previously considered models, but explain well features of pair-distribution functions of highly densified silica glass and molten basalt at high pressure. Built of four, five-, and six-coordinated silicon, coesite-IV and coesite-V contain SiO6 octahedra, which, at odds with 3rd Pauling's rule, are connected through common faces. Our results suggest that possible silicate liquids in Earth's lower mantle may have complex structures making them more compressible than previously supposed.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bykova, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bykov, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cernok, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tidholm, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Simak, S. I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hellman, O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Belov, M. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Abrikosov, I. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Liermann, H. -P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hanfland, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Prakapenka, V. B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Prescher, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dubrovinskaia, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dubrovinsky, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-165695
DOI:	10.1038/s41467-018-07265-z
Journal or Publication Title:	Nat. Commun.
Volume:	9
Date:	2018
Publisher:	NATURE PUBLISHING GROUP
Place of Publication:	LONDON
ISSN:	2041-1723
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language X-RAY-DIFFRACTION; MOLECULAR-DYNAMICS; PHASE-TRANSITIONS; MGSIO3 GLASS; SIO2; CHEMISTRY; LIQUID Multiple languages Multidisciplinary Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16569