Oxygen-17 nuclear magnetic resonance measurements on apatite-type lanthanum silicate (La9.33(SiO4)6O2)

Kiyono, Hajime; Matsuda, Y.; Shimada, Toshihiro; Ando, Mariko; Oikawa, Itaru; Maekawa, Hideki; Nakayama, Susumu; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Florian, Pierre; Massiot, Dominique

doi:10.1016/j.ssi.2012.09.016

Cited by 14 publications

(10 citation statements)

References 25 publications

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“…The latter assignment is consistent with the observation of interstitial O species in previously reported silicate-and germanate-based rare earth apatite SOFC materials. 47,49 It can be observed that upon dehydration of these systems both of these interstitial species are essentially removed, with the more complete removal of the Si-O-Si/Si-OH interstitial species being observed from the La 8 Sr 2 Si 6 O 26 system, suggesting that this component is mostly related to Si-OH (see Fig. 10(b)).…”

Section: Dalton Transactions Papermentioning

confidence: 95%

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La_9.6Si₆O_26.4 and La₈Sr₂Si₆O₂₆, and their hydrated phases

et al. 2016

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Apatite silicates are attracting significant interest as potential SOFC electrolyte materials. They are non-conventional oxide ion conductors in the sense that oxide ion interstitials, rather than vacancies, are the key defects. In this work we compare the structures of La9.6Si6O26.4 and La8Sr2Si6O26, both before and after hydration in order to gather information about the location of the interstitial oxide ion site. Neutron diffraction structural studies suggest that in the as-prepared La8Sr2Si6O26 and hydrated La8Sr2Si6O26, the interstitial oxide ion sites are close to the apatite channel centre. For La9.6Si6O26.4, a similar site close to the channel centre is observed, but on hydration of this particular sample, the interstitial site is shown to be significantly displaced away from the channel centre towards the SiO4 units. This can be explained by the need for additional displacement from the channel centre to accommodate the large amount of interstitial anions in this hydrated phase. The solid state (29)Si MAS NMR spectra are shown to be very sensitive to the different speciation exhibited by the La8Sr2Si6O26 and La9.6Si6O26.4 systems, with the former being dominated by regular SiO4 framework species and the latter being dominated by interruptions to this network caused by cation vacancies and interstitials. The corresponding (17)O MAS NMR study identifies a strong signal from the O atoms of the SiO4 groups, thus demonstrating that all of the O species in these systems are exchangeable O under heterogeneous gas phase conditions. In addition, interstitial O species attributed to pendant OH linkages on the Si positions are clearly identified and resolved, and these are removed on dehydration. This observation and assignment is corroborated by corresponding (1)H MAS NMR measurements. Overall the neutron diffraction work indicates that the interstitial site location in these apatite silicates depends on the anion content with progressive displacement towards the SiO4 tetrahedra on increasing anion content, while the observation of exchangeable O on the SiO4 groups is consistent with prior modelling predictions as to the importance on the silicate units in the conduction process.

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Section: Dalton Transactions Papermentioning

confidence: 95%

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La_9.6Si₆O_26.4 and La₈Sr₂Si₆O₂₆, and their hydrated phases

et al. 2016

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“…Despite the very low inherent receptivity of 17 O SSNMR spectroscopy, there is a sizable body of high-quality work; the reader is directed toward several comprehensive reviews of the field. − There has recently been significant progress in 17 O SSNMR, including the development of 17 O dynamic nuclear polarization (DNP) SSNMR spectroscopy. − 17 O SSNMR has been used to investigate the structure and disorder in variety of glasses, − along with water, ice, hydrated compounds, and clathrate hydrates. − This technique has been applied across very diverse chemical fields, ,− including organic and biological molecules, ,,,,, drugs and pharmaceuticals, , and battery systems. , …”

Section: Introductionmentioning

confidence: 99%

Inspecting the Structure and Formation of Molecular Sieve SAPO-34 via ¹⁷O Solid-State NMR Spectroscopy

et al. 2018

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Silicoaluminophosphates (SAPOs) are microporous frameworks with Brønsted acid sites that can be used as acidic catalysts. A firm understanding of SAPO structure, formation, and crystallinity is necessary for understanding and expanding SAPO applications in heterogeneous catalysis. Solid-state 17O NMR (SSNMR) spectroscopy is an ideal tool to probe structure and formation of SAPO-based materials; the 17O quadrupolar and chemical shift interactions are exquisitely sensitive to local electronic and magnetic environments. In this work, a pure trigonal SAPO-34 molecular sieve synthesized via the dry-gel conversion (DGC) method was investigated using a combination of 17O magic-angle spinning, 17O triple-quantum magic-angle spinning, 17O[27Al] transfer of population in double-resonance, and 17O[31P] rotational-echo double-resonance SSNMR spectroscopy, complemented by powder X-ray diffraction along with 27Al, 29Si, and 31P multinuclear SSNMR experiments. The four observed 17O resonances were simulated to extract NMR parameters, with each resonance assigned to individual oxygen local environments and connectivities in SAPO-34. The incorporation of oxygen from 17O-labeled water (i.e., H2 17O) during the DGC formation of pure trigonal SAPO-34 has also been investigated at various time intervals and stages of crystallization using 17O SSNMR. There is direct involvement of 17O-enriched water vapor during the DGC crystallization process of trigonal SAPO-34. The initial dry gel is amorphous, transforming to a crystalline layered AlPO4 phase during the first hour of heating and then progressing to a semicrystalline phase after 4 h of heating; formation of the crystalline trigonal SAPO-34 product was found to be complete after 2 days.

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“…Apparent exchange of O(1), O(2) and O(3) oxide ions bonded to Si was observed by 17 O NMR measurement on La 9.33 Si 6 O 26 by KIYINO et al [22], while it was not observed for oxide ion on the isolated site O(4). The results indicate that oxide ions bonded to Si at the position O(1), O (2) and O(3) are the main diffusion species in the oxide ion conductivity.…”

Section: Apatite-type Lanthanium Silicatesmentioning

confidence: 94%

Rare-earth Element-bearing Apatites and Oxyapatites

Ptáček¹

2016

Apatites and Their Synthetic Analogues - Synthesis, Structure, Properties and Applications

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A number of prepared alkaline-earth-rare-earth silicates and germanates also have the structure of apatite type. The fifth chapter of this book then continues with description of synthetic compounds of apatite structure. Attention will be directed to description of rare-earth element bearing apatites and oxyapatites. The structure, properties and preparation of apatite-type silicates, germanates and borates were described. This chapter gives also description of oxygen-rich apatites, which are promising material for electrolytes in solid oxide fuel cells and sensors and explain the basic concepts between structure and conductivity of these compounds. The additional information about application of apatites is given in the last chapter of this book. Furthermore, N-apatite, REE vanadocalcic apatite and apatite type yttrium phosphates were described.

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Oxygen-17 nuclear magnetic resonance measurements on apatite-type lanthanum silicate (La9.33(SiO4)6O2)

Cited by 14 publications

References 25 publications

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La_9.6Si₆O_26.4 and La₈Sr₂Si₆O₂₆, and their hydrated phases

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La_9.6Si₆O_26.4 and La₈Sr₂Si₆O₂₆, and their hydrated phases

Inspecting the Structure and Formation of Molecular Sieve SAPO-34 via ¹⁷O Solid-State NMR Spectroscopy

Rare-earth Element-bearing Apatites and Oxyapatites

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Oxygen-17 nuclear magnetic resonance measurements on apatite-type lanthanum silicate (La9.33(SiO4)6O2)

Cited by 14 publications

References 25 publications

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La9.6Si6O26.4 and La8Sr2Si6O26, and their hydrated phases

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La9.6Si6O26.4 and La8Sr2Si6O26, and their hydrated phases

Inspecting the Structure and Formation of Molecular Sieve SAPO-34 via 17O Solid-State NMR Spectroscopy

Rare-earth Element-bearing Apatites and Oxyapatites

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Product

Resources

About

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La_9.6Si₆O_26.4 and La₈Sr₂Si₆O₂₆, and their hydrated phases

Neutron diffraction and multinuclear solid state NMR investigation into the structures of oxide ion conducting La_9.6Si₆O_26.4 and La₈Sr₂Si₆O₂₆, and their hydrated phases

Inspecting the Structure and Formation of Molecular Sieve SAPO-34 via ¹⁷O Solid-State NMR Spectroscopy