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Title: Characterization of cation environments in polycrystalline forsterite by Mg-25 MAS, MQMAS, and QCPMG NMR

Abstract

Forsterite (Mg2SiO4) is a silicate mineral frequently studied in the Earth sciences as it has a simple crystal structure and fast dissolution kinetics (elemental release rates under typical conditions on the order of 10-7 mol/m2/s1). During the dissolution process, spectroscopic techniques are often utilized to augment solution chemical analysis and to provide data for determining reaction mechanisms. Nuclear magnetic resonance (NMR) is able to interrogate the local bonding arrangement and coordination of a particular nuclide to obtain in structural information. Although previous NMR studies have focused on the silicon and oxygen environments in forsterite, studies focusing on the two nonequivalent magnesium environments in forsterite are limited to a few single-crystal studies. In this study, we present the results of 25Mg MAS, MQMAS, and static QCMG experiments performed on a powdered sample of pure synthetic forsterite. We also present spectral fits obtained from simulation software packages, which directly provide quadrupolar parameters for 25Mg nuclei occupying each of the two nonequivalent magnesium sites in the forsterite structure. These results are compared to calculations of the electric field gradient tenor conducted in previous ab initio studies to make definitive assignments correlating each peak to their respective magnesium site in the forsterite structure. Althoughmore » previous NMR investigations of forsterite have focused on single-crystal samples, we have focused on powdered forsterite as the increased surface area of powdered samples makes them more amenable to laboratory-scale dissolution studies and, ultimately, the products from chemical weathering may be monitored an quantified.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1000111
Report Number(s):
PNNL-SA-75288
Journal ID: ISSN 0003-004X; AMMIAY; 25431; 400412000; TRN: US201024%%308
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
American Mineralogist, 95(11-12):1601-1607
Additional Journal Information:
Journal Volume: 95; Journal Issue: 11-12; Journal ID: ISSN 0003-004X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BONDING; CATIONS; CHEMICAL ANALYSIS; CRYSTAL STRUCTURE; DISSOLUTION; ELECTRIC FIELDS; FOCUSING; ISOTOPES; KINETICS; MAGNESIUM; NUCLEAR MAGNETIC RESONANCE; NUCLEI; OXYGEN; REACTION KINETICS; SILICATE MINERALS; SILICON; SURFACE AREA; WEATHERING; Forsterite; magnesium; Mg-25; NMR; MQMAS; QCPMG; HIGH-RESOLUTION NMR; ANGLE-SPINNING NMR; INTEGER; QUADRUPOLAR NUCLEI; DISSOLUTION RATES; O-17 NMR; SPECTROSCOPY; SOLIDS; SENSITIVITY; OLIVINE; MG2SIO4; Environmental Molecular Sciences Laboratory

Citation Formats

Davis, Michael C, Brouwer, William J, Lipton, Andrew S, Gan, Zhehong, and Mueller, Karl T. Characterization of cation environments in polycrystalline forsterite by Mg-25 MAS, MQMAS, and QCPMG NMR. United States: N. p., 2010. Web. doi:10.2138/am.2010.3403.
Davis, Michael C, Brouwer, William J, Lipton, Andrew S, Gan, Zhehong, & Mueller, Karl T. Characterization of cation environments in polycrystalline forsterite by Mg-25 MAS, MQMAS, and QCPMG NMR. United States. https://doi.org/10.2138/am.2010.3403
Davis, Michael C, Brouwer, William J, Lipton, Andrew S, Gan, Zhehong, and Mueller, Karl T. 2010. "Characterization of cation environments in polycrystalline forsterite by Mg-25 MAS, MQMAS, and QCPMG NMR". United States. https://doi.org/10.2138/am.2010.3403.
@article{osti_1000111,
title = {Characterization of cation environments in polycrystalline forsterite by Mg-25 MAS, MQMAS, and QCPMG NMR},
author = {Davis, Michael C and Brouwer, William J and Lipton, Andrew S and Gan, Zhehong and Mueller, Karl T},
abstractNote = {Forsterite (Mg2SiO4) is a silicate mineral frequently studied in the Earth sciences as it has a simple crystal structure and fast dissolution kinetics (elemental release rates under typical conditions on the order of 10-7 mol/m2/s1). During the dissolution process, spectroscopic techniques are often utilized to augment solution chemical analysis and to provide data for determining reaction mechanisms. Nuclear magnetic resonance (NMR) is able to interrogate the local bonding arrangement and coordination of a particular nuclide to obtain in structural information. Although previous NMR studies have focused on the silicon and oxygen environments in forsterite, studies focusing on the two nonequivalent magnesium environments in forsterite are limited to a few single-crystal studies. In this study, we present the results of 25Mg MAS, MQMAS, and static QCMG experiments performed on a powdered sample of pure synthetic forsterite. We also present spectral fits obtained from simulation software packages, which directly provide quadrupolar parameters for 25Mg nuclei occupying each of the two nonequivalent magnesium sites in the forsterite structure. These results are compared to calculations of the electric field gradient tenor conducted in previous ab initio studies to make definitive assignments correlating each peak to their respective magnesium site in the forsterite structure. Although previous NMR investigations of forsterite have focused on single-crystal samples, we have focused on powdered forsterite as the increased surface area of powdered samples makes them more amenable to laboratory-scale dissolution studies and, ultimately, the products from chemical weathering may be monitored an quantified.},
doi = {10.2138/am.2010.3403},
url = {https://www.osti.gov/biblio/1000111}, journal = {American Mineralogist, 95(11-12):1601-1607},
issn = {0003-004X},
number = 11-12,
volume = 95,
place = {United States},
year = {Mon Nov 01 00:00:00 EDT 2010},
month = {Mon Nov 01 00:00:00 EDT 2010}
}