Chromatographic studies of the structures of amorphous phosphates: a review

Sales, B. C.; Boatner, L. A.; Ramey, J. O.

doi:10.1016/s0022-3093(99)00644-4

Cited by 41 publications

(34 citation statements)

References 30 publications

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“…A significant difference is found for the OO of the glass with 27 mole% Ga 2 O 3 . It remembers to the diffraction study of an Al(PO 3 ) 3 glass [26], where also a tail of the O-O peak was obtained. It was argued that the short edges of AlO 6 octahedra contribute to this peak.…”

Section: Discussionmentioning

confidence: 81%

The Structure of Gallium Phosphate Glasses by High-energy X-ray Diffraction

Hoppe

Ilieva²,

Neuefeindb³

2002

Zeitschrift Für Naturforschung A

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X-ray diffraction experiments are used to obtain short-range order information of gallium phosphate glasses of meta-and pyrophosphate compositions. Parameters of the first-neighbor peaks, such as coordination numbers and distances, are obtained. A strong decrease of the Ga-O coordination number from 6.0 0.2 to 4.6 0.2 upon Ga 2 O 3 addition is found, which is accompanied by a shortening of the Ga-O distances. Only GaO 6 octahedra exist at the metaphosphate composition. Close to the pyrophosphate composition, the majority of Ga atoms occupies already tetrahedral sites. The Ga-O coordination number behaves equivalent with the ratio TO = (O T )/ (Ga), thus, with the number (O T ) of terminal oxygen atoms (O T ) in phosphorus-O T bonds which are available for the coordination of each Ga atom. Thus, P-O T -Ga bridges are formed for all O T atoms. The GaO polyhedra neither share O T atoms nor form Ga-O-Ga bridges. With increasing fraction of GaO 4 tetrahedra and decreasing lengths of the phosphate chains the network expands.

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Section: Discussionmentioning

confidence: 81%

The Structure of Gallium Phosphate Glasses by High-energy X-ray Diffraction

Hoppe

Ilieva²,

Neuefeindb³

2002

Zeitschrift Für Naturforschung A

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“…In the study by Ruiz Hernandez et al 11 , they are only formed at the interface z > 14 Å, with very few cations in the first coordination sphere, and at almost all times disconnected from the main phosphate network. Experimentally it is known that, once in solution, the phosphate rings are very stable 53,54 , but their very low concentrations observed in the MD, the lack of solvent in the model employed and no other information from higher levels of theory, make it difficult to predict their impact.…”

Section: Discussionmentioning

confidence: 99%

Structures and properties of phosphate-based bioactive glasses from computer simulation: a review

et al. 2017

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This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication.Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available.You can find more information about Accepted Manuscripts in the author guidelines.Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the ethical guidelines, outlined in our author and reviewer resource centre, still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. ture at the surface, and how this changes from that of the bulk.In the past few years, our groups and others have extensively used state-of-the-art highperformance computing methods, usually molecular dynamics (MD) simulations, to characterise the structure and properties of PBGs. In molecular dynamics, the individual atoms move due to the interatomic forces they experience from other atoms. Because the full three-dimensional structure of the material is available at all times, an MD trajectory contains a great deal of information from which the material's properties may be deduced. Our work has involved new methodological developments in the form of a new model of the phosphate interatomic forces 9 , and MD simulations have given new insight into the structural motifs which affect the dissolution which are not accessible to experimental methods 10 . Recently, the different properties of PBG at the surface of the glass, from where the dissolution takes place have been shown, which will also be important in unravelling the full connections between structure and dissolution 11 . Molecular dynamics methods for preparation of glassesA full review of molecular dynamics methods is beyond the scope of this paper; the reader is invited to turn to relevant books 12,13 . Broadly, there are two types of molecular dynamics used to prepare realistic glass models: classical and first-principles. In classical MD, the interatomic forces are represented by an empirical expression with a small number of parameters which are chosen to reproduce existing data on the material. This method has the advantage of being relatively easy to implement and computationally inexpensive, allowing for large models (typically ∼ 10 3 − 10 4 atoms) to be simulated over long timescales (typically ns). The disadvantage is that the accuracy of the simulation is limited by the accuracy of the approximations of the interatomic potential model. First-principles MD, by contrast, uses a quantum-mechanical expression for th...

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“…In Mg phosphate glasses, the existence of these rings was assumed [27] to explain the so-called phosphate anomaly [28]. There have been NMR [29] and liquid chromatography studies [30] that provide evidence for small quantities of ring structures in different phosphate glasses. However, Figs.…”

Section: Small-scale Heterogeneities In Magnesium and Zinc Phosphate mentioning

confidence: 99%

“…However, Figs. 3 and 5 show that the scattering effect appears across a widely extended polyphosphate range, i.e., even in that range where the fraction of Q 2 sites, the presence of which is necessary to form rings, is very small or equal to zero [6,7,30], respectively. In Ref.…”

Section: Small-scale Heterogeneities In Magnesium and Zinc Phosphate mentioning

confidence: 99%

The structure of phosphate glass evidenced by small angle X-ray scattering

Walter

Goerigk

Rüssel

2006

Journal of Non-Crystalline Solids

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Numerous phosphate glass systems with compositions covering the entire glass forming range have been examined by small angle Xray scattering. The experiments were carried out in a widely extended interval of s values between 0.055 and 31 nm À1 . A small angle scattering effect was detected for all samples investigated with the exception of the aluminium metaphosphate glass. The small angle scattering recorded indicates the presence of two differently-sized heterogeneity regions of electron density. The small-scale heterogeneities are present in magnesium and zinc phosphate glasses only. Their size is about 1 nm diameter in the magnesium and about 2 nm in the zinc phosphate glasses. The species do not result from liquid-liquid phase separation. Examinations to extract information on the nature of these heterogeneity regions are described in detail. There is no fundamental knowledge on the large-scale heterogeneities established. The small angle scattering suggests that their occurrence is related to water contamination. Anomalous small angle X-ray scattering experiments of a series of zinc polyphosphate glasses and a strontium metaphosphate glass sample are performed to examine the distribution of the Zn or Sr atoms, respectively.

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Chromatographic studies of the structures of amorphous phosphates: a review

Cited by 41 publications

References 30 publications

The Structure of Gallium Phosphate Glasses by High-energy X-ray Diffraction

The Structure of Gallium Phosphate Glasses by High-energy X-ray Diffraction

Structures and properties of phosphate-based bioactive glasses from computer simulation: a review

The structure of phosphate glass evidenced by small angle X-ray scattering

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