TY  - JOUR
AU  - Kohara, S.
AU  - Akola, J.
AU  - Morita, H.
AU  - Suzuya, K.
AU  - Weber, J.K.R.
AU  - Wilding, M.C.
AU  - Benmore, C.J.
TI  - Relationship between topological order and glass forming ability in densely packed enstatite and forsterite composition glasses
JO  - Proceedings of the National Academy of Sciences of the United States of America
VL  - 108
SN  - 0027-8424
CY  - Washington, DC
PB  - Academy
M1  - PreJuSER-19949
SP  - 14780 - 14785
PY  - 2011
N1  - We thank Dr. Jan Swenson for providing us with the atomic configuration of 3Na<INF>2</INF>O-4SiO<INF>2</INF> and 3CaO-4SiO<INF>2</INF> glasses. We thank Mr. Hiroyuki Fujii for helping the development of software for ring statistics calculations. The synchrotron radiation experiment was carried out with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2006B1461) and all DFT calculations were carried out on Juropa (Xeon 5570) and Cray XT4/XT5 supercomputers in the Forschungszentrum Julich (FZJ, Germany) and CSC (Espoo, Finland) with grants from FZJ, the John von Neumann Institute for Computing, and CSC. This work was supported by the Department of Energy, Division of Materials Science, Office of Basic Energy Science, under Contract number DE-AC02-06CH11357 and by Grant-in-Aid for Scientific Research on Innovative Areas (Grant No. 20103004) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. S. K. and J.A. are supported by the Japan Science and Technology Agency and the Academy of Finland via the Strategic Japanese-Finland Cooperative Program on "Functional Materials."
AB  - The atomic structures of magnesium silicate melts are key to understanding processes related to the evolution of the Earth's mantle and represent precursors to the formation of most igneous rocks. Magnesium silicate compositions also represent a major component of many glass ceramics, and depending on their composition can span the entire fragility range of glass formation. The silica rich enstatite (MgSiO(3)) composition is a good glass former, whereas the forsterite (Mg(2)SiO(4)) composition is at the limit of glass formation. Here, the structure of MgSiO(3) and Mg(2)SiO(4) composition glasses obtained from levitated liquids have been modeled using Reverse Monte Carlo fits to diffraction data and by density functional theory. A ring statistics analysis suggests that the lower glass forming ability of the Mg(2)SiO(4) glass is associated with a topologically ordered and very narrow ring distribution. The MgO(x) polyhedra have a variety of irregular shapes in MgSiO(3) and Mg(2)SiO(4) glasses and a cavity analysis demonstrates that both glasses have almost no free volume due to a large contribution from edge sharing of MgO(x)-MgO(x) polyhedra. It is found that while the atomic volume of Mg cations in the glasses increases compared to that of the crystalline phases, the number of Mg-O contacts is reduced, although the effective chemical interaction of Mg(2+) remains similar. This unusual structure-property relation of Mg(2)SiO(4) glass demonstrates that by using containerless processing it may be possible to synthesize new families of dense glasses and glass ceramics with zero porosity.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:21873237
C2  - pmc:PMC3169147
UR  - <Go to ISI:>//WOS:000294543400020
DO  - DOI:10.1073/pnas.1104692108
UR  - https://juser.fz-juelich.de/record/19949
ER  -