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Vasconcelos F, Cristol S, Paul JF, Delevoye L, Mauri F, Charpentier T, Le Caër G. Extended Czjzek model applied to NMR parameter distributions in sodium metaphosphate glass. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:255402. [PMID: 23719213 DOI: 10.1088/0953-8984/25/25/255402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The extended Czjzek model (ECM) is applied to the distribution of NMR parameters of a simple glass model (sodium metaphosphate, NaPO3) obtained by molecular dynamics (MD) simulations. Accurate NMR tensors, electric field gradient (EFG) and chemical shift anisotropy (CSA) are calculated from density functional theory (DFT) within the well-established PAW/GIPAW framework. The theoretical results are compared to experimental high-resolution solid-state NMR data and are used to validate the considered structural model. The distributions of the calculated coupling constant C(Q) is proportional to |V(zz)| and the asymmetry parameter η(Q) that characterize the quadrupolar interaction are discussed in terms of structural considerations with the help of a simple point charge model. Finally, the ECM analysis is shown to be relevant for studying the distribution of CSA tensor parameters and gives new insight into the structural characterization of disordered systems by solid-state NMR.
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Affiliation(s)
- Filipe Vasconcelos
- Unité de Catalyse et Chimie du Solide, UMR CNRS 8181, École Nationale Supérieure de Chimie de Lille, Université de Lille, BP Villeneuve d'Ascq, France.
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8
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Parsons AJ, Ahmed I, Rudd CD, Cuello GJ, Pellegrini E, Richard D, Johnson MR. Neutron scattering and ab initio molecular dynamics study of cross-linking in biomedical phosphate glasses. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:485403. [PMID: 21406745 DOI: 10.1088/0953-8984/22/48/485403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Details of the microscopic structure of phosphate glasses destined for biomedical applications, which include sodium, magnesium and calcium cations, have been obtained from the static structure factor measured by means of neutron scattering. A complementary, molecular dynamics study has been performed on a range of phosphate glasses using density functional theory methods, which allow structural fluctuations, including bond breaking, in the liquid phase before quenching to the glass phase. Good agreement between experiment and simulation allows the molecular dynamics trajectories to be analysed in detail. In particular, attention is focused on the cross-linking of divalent cations in contrast with the structural aspects associated with monovalent cations. Magnesium cations are found equidistant and bridging between the phosphorus atoms of different phosphate chains, leading to a shorter phosphorus-phosphorus second neighbour distance (that is, a more compact packing of neighbouring phosphate chains) compared to the effect of sodium cations. Calcium cations show behaviour intermediate between those of magnesium and sodium. Molecular dynamics simulations give access to the cation mobility, which is lowest for magnesium, reflecting its structural, cross-linking role.
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Affiliation(s)
- A J Parsons
- Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham, UK.
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Wetherall KM, Pickup DM, Newport RJ, Mountjoy G. The structure of calcium metaphosphate glass obtained from x-ray and neutron diffraction and reverse Monte Carlo modelling. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:035109. [PMID: 21817268 DOI: 10.1088/0953-8984/21/3/035109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The short range structure of (CaO)(0.5)(P(2)O(5))(0.5) glass has been studied using x-ray and neutron diffraction and modelled using the reverse Monte Carlo method. Using this combination of techniques has allowed six interatomic correlations to be distinguished and fitted to obtain a set of bond lengths and coordination numbers that describe the structure of the glass. The glass consists of metaphosphate chains of phosphate tetrahedra and each phosphate unit has two non-bridging oxygen atoms available for coordination with Ca. The Ca-O correlation was fitted with two peaks at 2.35 and 2.86 Å, representing a broad distribution of bond lengths. The total Ca-O coordination is 6.9 and is consistent with distorted polyhedral units such as capped octahedra or capped trigonal prisms. It is found that most non-bridging oxygen atoms are bonded to two calcium atoms. All of these observations are consistent with Hoppe's model for phosphate glasses. Furthermore, the medium range order is revealed to consist of phosphate chains intertwined with apparently elongated clusters of Ca ions, and the Ca-O and Ca-P correlations contributed significantly to the first sharp diffraction peak in x-ray diffraction.
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Affiliation(s)
- K M Wetherall
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK
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Alam TM, McLaughlin J, Click CC, Conzone S, Brow RK, Boyle TJ, Zwanziger JW. Investigation of Sodium Distribution in Phosphate Glasses Using Spin−Echo 23Na NMR. J Phys Chem B 2000. [DOI: 10.1021/jp9931509] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Todd M. Alam
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
| | - Jay McLaughlin
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
| | - Carol C. Click
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
| | - Sam Conzone
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
| | - Richard K. Brow
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
| | - Timothy J. Boyle
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
| | - J. W. Zwanziger
- Sandia National Laboratories, Department of Material Aging and Reliability, Albuquerque, New Mexico 87185-1407, Indiana University, Department of Chemistry, Bloomington, Indiana 47405, University of MissouriRolla, Ceramic Engineering Department, Rolla, Missouri 65409-0330, and Sandia National Laboratories, Materials Processing Department, Advanced Materials Laboratory, 1001 University Boulevard SE., Albuquerque, New Mexico 87106-1349
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