Universität zu Köln

Drewitt, James W. E., Barnes, Adrian C., Jahn, Sandro ORCID: 0000-0002-2137-8833, Kohn, Simon C., Walter, Michael J., Novikov, Alexey N., Neuville, Daniel R., Fischer, Henry E. and Hennet, Louis (2017). Structure of liquid tricalcium aluminate. Phys. Rev. B, 95 (6). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9969

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Abstract

The atomic-scale structure of aerodynamically levitated and laser-heated liquid tricalcium aluminate (Ca3Al2O6) was measured at 2073(30) K by using the method of neutron diffraction with Ca isotope substitution (NDIS). The results enable the detailed resolution of the local coordination environment around calcium and aluminum atoms, including the direct determination of the liquid partial structure factor, S-CaCa(Q), and partial pair distribution function, (gCaCa)(r). Molecular dynamics (MD) simulation and reverse Monte Carlo (RMC) refinement methods were employed to obtain a detailed atomistic model of the liquid structure. The composition Ca3Al2O6 lies at the CaO-rich limit of the CaO: Al2O3 glass-forming system. Our results show that, although significantly depolymerized, liquid Ca3Al2O6 is largely composed of AlO4 tetrahedra forming an infinite network with a slightly higher fraction of bridging oxygen atoms than expected for the composition. Calcium-centered polyhedra exhibit a wide distribution of four-to sevenfold coordinated sites, with higher coordinated calcium preferentially bonding to bridging oxygens. Analysis of the MD configuration reveals the presence of similar to 10% unconnected AlO4 monomers and Al2O7 dimers in the liquid. As the CaO concentration increases, the number of these isolated units increases, such that the upper value for the glass-forming composition of CaO: Al2O3 liquids could be described in terms of a percolation threshold at which the glass can no longer support the formation of an infinitely connected AlO4 network.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Drewitt, James W. E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Barnes, Adrian C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Jahn, Sandro UNSPECIFIED orcid.org/0000-0002-2137-8833 UNSPECIFIED Kohn, Simon C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Walter, Michael J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Novikov, Alexey N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Neuville, Daniel R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fischer, Henry E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hennet, Louis UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-241896
DOI:	10.1103/PhysRevB.95.064203
Journal or Publication Title:	Phys. Rev. B
Volume:	95
Number:	6
Date:	2017
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9969
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language X-RAY-DIFFRACTION; NEUTRON-DIFFRACTION; CONSTRAINT THEORY; CALCIUM; GLASSES; MELTS; ABSORPTION; SILICA; RAMAN; AL Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/24189