TY - JOUR
T1 - Structure of diopside, enstatite and magnesium aluminosilicate glasses: A joint approach using neutron and x-ray diffraction and solid-state NMR
AU - Mohammadi, Hesameddin
AU - Mendes Da Silva, Rita
AU - Zeidler, Anita
AU - Gammond, Lawrence V. D.
AU - Gehlhaar, Florian
AU - de Oliveira Jr, Marcos
AU - Damasceno, Hugo
AU - Eckert, Hellmut
AU - Youngman, Randall E.
AU - Aitken, Bruce G.
AU - Fischer, Henry E.
AU - Kohlmann, Holger
AU - Cormier, Laurent
AU - Benmore, Chris J
AU - Salmon, Philip
N1 - Funding Information:
H.M. was supported by Corning Inc. (Agreement No. CM00002159/SA/01). R.M.D.S. was supported by the Royal Society (Grant No. RGF/EA/180060). A.Z. was supported by a Royal Society-EPSRC Dorothy Hodgkin Research Fellowship. L.V.D.G. acknowledges funding and support from the EPSRC Centre for Doctoral Training in Condensed Matter Physics (CDT-CMP), Grant No. EP/L015544/1, the Science and Technology Facilities Council (STFC) and Diamond Light Source Ltd. (Reference No. STU0173). P.S.S. and A.Z. are grateful to Corning Inc. for the award of Gordon S. Fulcher Distinguished Scholarships under which this work was conceived. Funding of this work by FAPESP, Project No. 2013/07793-6, is gratefully acknowledged. M.d.O., Jr. and H.E. acknowledge the National Council for Scientific and Technological Development (CNPq, Grant Nos. 311069/2020-7 and 310870/2020-8, respectively). H.D. acknowledges personal fellowship support from CNPq and Nippon Electric Glass. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. We acknowledge use of the Inorganic Crystal Structure Database accessed via the Chemical Database Service funded by the Engineering and Physical Sciences Research Council (EPSRC) and hosted by the Royal Society of Chemistry.
PY - 2022/12/7
Y1 - 2022/12/7
N2 - Neutron diffraction with magnesium isotope substitution, high energy x-ray diffraction, and 29Si, 27Al, and 25Mg solid-state nuclear magnetic resonance (NMR) spectroscopy were used to measure the structure of glassy diopside (CaMgSi2O6), enstatite (MgSiO3), and four (MgO)x(Al2O3)y(SiO2)1-x-y glasses, with x = 0.375 or 0.25 along the 50 mol. % silica tie-line (1 - x - y = 0.5) or with x = 0.3 or 0.2 along the 60 mol. % silica tie-line (1 - x - y = 0.6). The bound coherent neutron scattering length of the isotope 25Mg was remeasured, and the value of 3.720(12) fm was obtained from a Rietveld refinement of the powder diffraction patterns measured for crystalline 25MgO. The diffraction results for the glasses show a broad asymmetric distribution of Mg-O nearest-neighbors with a coordination number of 4.40(4) and 4.46(4) for the diopside and enstatite glasses, respectively. As magnesia is replaced by alumina along a tie-line with 50 or 60 mol. % silica, the Mg-O coordination number increases with the weighted bond distance as less Mg2+ ions adopt a network-modifying role and more of these ions adopt a predominantly charge-compensating role. 25Mg magic angle spinning (MAS) NMR results could not resolve the different coordination environments of Mg2+ under the employed field strength (14.1 T) and spinning rate (20 kHz). The results emphasize the power of neutron diffraction with isotope substitution to provide unambiguous site-specific information on the coordination environment of magnesium in disordered materials.
AB - Neutron diffraction with magnesium isotope substitution, high energy x-ray diffraction, and 29Si, 27Al, and 25Mg solid-state nuclear magnetic resonance (NMR) spectroscopy were used to measure the structure of glassy diopside (CaMgSi2O6), enstatite (MgSiO3), and four (MgO)x(Al2O3)y(SiO2)1-x-y glasses, with x = 0.375 or 0.25 along the 50 mol. % silica tie-line (1 - x - y = 0.5) or with x = 0.3 or 0.2 along the 60 mol. % silica tie-line (1 - x - y = 0.6). The bound coherent neutron scattering length of the isotope 25Mg was remeasured, and the value of 3.720(12) fm was obtained from a Rietveld refinement of the powder diffraction patterns measured for crystalline 25MgO. The diffraction results for the glasses show a broad asymmetric distribution of Mg-O nearest-neighbors with a coordination number of 4.40(4) and 4.46(4) for the diopside and enstatite glasses, respectively. As magnesia is replaced by alumina along a tie-line with 50 or 60 mol. % silica, the Mg-O coordination number increases with the weighted bond distance as less Mg2+ ions adopt a network-modifying role and more of these ions adopt a predominantly charge-compensating role. 25Mg magic angle spinning (MAS) NMR results could not resolve the different coordination environments of Mg2+ under the employed field strength (14.1 T) and spinning rate (20 kHz). The results emphasize the power of neutron diffraction with isotope substitution to provide unambiguous site-specific information on the coordination environment of magnesium in disordered materials.
UR - http://www.scopus.com/inward/record.url?scp=85143994983&partnerID=8YFLogxK
U2 - 10.1063/5.0125879
DO - 10.1063/5.0125879
M3 - Article
VL - 157
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 21
M1 - 214503
ER -