Glasse aluminophosphate

Key Words P-31 solid-state NMR, 31P CP/MAS, Ultra-fast MAS, Phosphorylated amino acids, Nucleotides, Nucleic acids, Phosphate glasses, Aluminophosphates, Molecular sieves, Catalysts, Polyoxometalate (POM), Metal-organic framework (MOF), Inclusion complexes. 

It is interesting that this cement has been known for over 100 years and yet certain features of its chemistry remain obscure. The exact nature of the matrix is still a matter for conjecture. It is known that the principal phase is amorphous, as a result of the presence of aluminium in the liquid. It is also known that after a lapse of time, crystallites sometimes form on the surface of the cement. A cement gel may be likened to a glass and this process of crystallization could be likened to the devitrification of a glass. Therefore, it is reasonable to suppose that the gel matrix is a zinc aluminophosphate and that entry of aluminium into the zinc phosphate matrix causes disorder and prevents crystallization. It is not so easy to accept the alternative explanation that there are two amorphous phases, one of aluminium phosphate and the other of zinc phosphate. This is because it is difficult to see how aluminium could act in this case to prevent zinc phosphate from crystallizing. 

Solid-state NMR spectroscopy was used for studying the formation of cubic mesoporous aluminophosphate thin films and powders. The analysis of the initial gel, the as-deposited materials and the thermally-treated materials elucidated the changes in the coordination of phosphorus and aluminium atoms and thus revealed how the framework formation and condensation proceeds. The consolidation process in thin films was different than the process in powders. Most probably this could be attributed to the effect of glass substrate. 

P and 27A1 MAS NMR spectra of aluminophosphate powders and of samples scratched from films were recorded on 600 MHz Varian NMR system equipped with a Varian 3.2 mm MAS probe. Fifty two-faced films deposited on glass slides were needed to obtain sufficient amount of material for NMR measurements. Larmor frequencies for phosphorus and aluminium at 14.1 T are 242.89 and 156.35 MHz, respectively. 

Aluminide alloys, 13 530 Aluminium powder, 10 738. See also Aluminum entries Aluminohydride derivatives, 13 624 Aluminohydrides, 13 621-624 Aluminophosphate zeolites, 14 98 Aluminosilicate gels, 16 830 Aluminosilicate glass, matrix for... 

Most of the detailed examinations were performed for the Synroc-C variety (Ringwood et al. 1988). Table 2 compares typical elemental leach rates (7-d MCC-1 test, 90 °C) from Synroc-C containing 10 wt% HLW calcine with those from borosilicate and aluminophosphate glasses, documenting that Synroc-C exhibits the lowest leach rates. 

Stefanovsky, S. V., Ivanov, I. A. Gulin, A. N. 1995. Aluminophosphate glasses with high sulfate content. Materials Research Society Symposium Proceedings, 353, 101-106. 

The application of P NMR to structural studies of alkali and alkaline earth phosphate and aluminophosphate glasses, fluorophosphate glasses and phosphorus oxynitride glasses has been reviewed by Kirkpatrick and Brow (1995). 

Network former connectivities have been explored in a variety of phosphate glasses containing aluminum or boron as a second network former component. A number of studies have been published on the sodium aluminophosphate glass system [82-85]. The Al NMR spectra of these glasses show three distinct resonances, attributable to AIO4, AIO5, and A106 units. All of these environments are intimately connected to phosphorus species, as revealed by 2D CPMAS het-eronuclear correlation and REDOR experiments [83]. 

Table 1 Approximate chemical shift regions ( 5 ppm) for species in aluminophosphate glasses. Here n refers to the number of bridging oxygen atoms and m is the number of A1 atoms bonded to P...

Solid-state FK and P / Na TRAPDOR NMR experiments have been used to investigate the spatial distribution of aluminium and sodium cations with respect to the phosphate backbone for a series of sodium aluminophosphate glasses, jcAl(2)0(4).50Na(2)0.(50—x)P205 (0 < x < 17.5). ... 

Takahashi, K., Binary Phosphate, Silicophosphate, Borophosphate, and Aluminophosphate Glasses, their Properties and Structure, a report presented at the 6th International Congress on Glass, Washington, July, 1962. 

J.M. Egan, R.M. Wenslow, K.T. Mueller, Mapping aluminum/phosphorus connectivities in aluminophosphate glasses,. Non-Cryst. Solids 261 (2000) 115—126. 

L. van Wiillen, G. Tricot, S. Wegner, An advanced NMR protocol for the stractural characterization of aluminophosphate glasses. Solid State Nucl. Magn. Reson. 32 (2007) 44-52. 

S. Wegner, L. van Wullen, G. Tricot, The structure of aluminophosphate glasses revisited application of modem solid state NMR strategies to determine structural motifs on intermediate length scales,. Non-Cryst. Solids 354 (2008) 1703—1714. 

L. van Wullen, S. Wegner, G. Tricot, Structural changes above the glass transition and crystallization in aluminophosphate glasses an in situ high-temperature MAS NMR study,. Phys. Chem. B 111 (2007) 7529-7534. 

Figure 6.6 F 1s spectra from a sodium aluminophosphate glass containing (a) 5 wt % F and (6) 15 wt % F. (From Reference 22.)...

NMR spectroscopy has been used to determine the hydroxyl content in erbium-doped aluminophosphates, aluminosilicate and fluorosilicate glasses. NMR studies of the organic template in mesostructured aluminophosphates have been reported. A comment on the 3Q-MAS/HETCOR... 

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