High-resolution silicon-29 nuclear magnetic resonance in the Y-Si-O-N system

Dupree, R.; Lewis, M. H.; Smith, Mark E.

doi:10.1021/ja00212a014

Cited by 68 publications

(44 citation statements)

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“…In fact, wellresolved 29 Si MAS-NMR spectra have been published for five out of six Y 2 Si 2 O 7 polymorphs [6,7] and for both Y 2 SiO 5 polymorphs [8,9] which agree well with the existing crystallographic data. Additional data are, nevertheless, needed to definitively determine the structural arrangement of the different polymorphs.…”

Section: Introductionsupporting

confidence: 85%

Revisiting Y2Si2O7 and Y2SiO5 polymorphic structures by 89Y MAS-NMR spectroscopy

Becerro

Escudero

Florian

et al. 2004

Journal of Solid State Chemistry

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Section: Introductionsupporting

confidence: 85%

Revisiting Y2Si2O7 and Y2SiO5 polymorphic structures by 89Y MAS-NMR spectroscopy

Becerro

Escudero

Florian

et al. 2004

Journal of Solid State Chemistry

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“…One broad peak at around −100 ppm was deconvoluted to three broad peaks centered at −110, −100, and −90 ppm that were assigned to silicon tetrahedral units of SiO 4 [29], HO–SiO 3 (Q3) [30], and SiO 3 N [31,32], respectively. …”

Section: Resultsmentioning

confidence: 99%

Synthesis of a Novel Polyethoxysilsesquiazane and Thermal Conversion into Ternary Silicon Oxynitride Ceramics with Enhanced Thermal Stability

et al. 2017

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A novel polyethoxysilsesquiazane ([EtOSi(NH)1.5]n, EtOSZ) was synthesized by ammonolysis at −78 °C of ethoxytrichlorosilane (EtOSiCl3), which was isolated by distillation as a reaction product of SiCl4 and EtOH. Attenuated total reflection-infra red (ATR-IR), 13C-, and 29Si-nuclear magnetic resonance (NMR) spectroscopic analyses of the ammonolysis product resulted in the detection of Si–NH–Si linkage and EtO group. The simultaneous thermogravimetric and mass spectrometry analyses of the EtOSZ under helium revealed cleavage of oxygen-carbon bond of the EtO group to evolve ethylene as a main gaseous species formed in-situ, which lead to the formation at 800 °C of quaternary amorphous Si–C–N with an extremely low carbon content (1.1 wt %) when compared to the theoretical EtOSZ (25.1 wt %). Subsequent heat treatment up to 1400 °C in N2 lead to the formation of X-ray amorphous ternary Si–O–N. Further heating to 1600 °C in N2 promoted crystallization and phase partitioning to afford Si2N2O nanocrystallites identified by the XRD and TEM analyses. The thermal stability up to 1400 °C of the amorphous state achieved for the ternary Si-O-N was further studied by chemical composition analysis, as well as X-ray photoelectron spectroscopy (XPS) and 29Si-NMR spectroscopic analyses, and the results were discussed aiming to develop a novel polymeric precursor for ternary amorphous Si–O–N ceramics with an enhanced thermal stability.

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“…The XANES/ELNES spectra of the Si-K, Si-L 2,3 , Y-K, Y-M 3,4 , O-K, and N-K edges in these materials are very sensitive to the rich local environment of the cations and anions described in this paper, and could be a better alternative to the NMR techniques used so far in determining the local structures. [21][22][23][24][25] The extensive overlap of the chemical shifts in the magic-angle spinning NMR spectra makes unambiguous assignment of local structural unit a rather difficult task. 22 Using the supercell method, 97 which accounts for the presence of the corehole, accurate XANES/ELNES spectra can be obtained and compared.…”

Section: Discussionmentioning

confidence: 99%

“…[21][22][23][24][25] The extensive overlap of the chemical shifts in the magic-angle spinning NMR spectra makes unambiguous assignment of local structural unit a rather difficult task. 22 Using the supercell method, 97 which accounts for the presence of the corehole, accurate XANES/ELNES spectra can be obtained and compared. In conjunction with the experimentally measured spectra on these systems, a much deeper understanding on the local bonding structure in these crystals is expected.…”

Section: Discussionmentioning

confidence: 99%

“…20 Detailed electronic structure calculation can also shed much light on possible local Si-O and Si-N bonding which has been subjected to several experimental investigations using 29+ Si nuclear magnetic resonance (NMR) with magic angle spinning technique. [21][22][23][24][25] The information obtained from these experiments so far is only qualitative at most. Their interpretation can be greatly facilitated by detailed theoretical calculations where the specific arrangements of Si-O and Si-N bonding are known.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure and bonding in the Y-Si-O-N quaternary crystals

et al. 2004

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The Y-Si-O-N quaternary crystals are an important part of structural ceramics. Their crystal structures are complex and not precisely determined. Little is known about their electronic structure and bonding which are indispensable for a fundamental understanding of structural ceramics. Within the equilibrium phase diagram of the SiO 2 -Y 2 O 3 -Si 3 N 4 system, there are only four known crystalline phases: Y 2 Si 3 N 4 O 3 (M-melilite), Y 4 Si 2 O 7 N 2 (J phase or N-YAM), YSiO 2 N (wallastonite), and Y 10 ͓SiO 4 ͔ 6 N 2 (N-apatite). With the possible exception of YSiO 2 N, these crystals have O / N disorder in that the exact positions of the anions cannot be uniquely determined. Using accurate ab initio total energy relaxation, the atomic positions of the lowest energy configurations in these crystals are determined. Based on the theoretically modeled structures, the electronic structure and bonding are investigated using the ab initio orthogonalized linear combination of atomic orbitals method, and are related to a variety of local cation-anion bonding configurations. These results are presented in the form of atom-resolved partial density of states, Mulliken effective charges and bond order values. Although the strong Si-N and Si-O bonding dominates in these crystals, it is also shown that Y-O and Y-N bonding are not negligible and should be a part of discussion of the overall bonding scheme in these crystals. It is concluded that Y 2 Si 3 N 4 O 3 has the strongest crystal bonding among the four crystals. In addition, the optical properties of these crystals are calculated using the ab initio wave functions. All four crystals are insulators with optical band gaps of 3.40, 3.19, 4.40, and 3.70 eV, respectively. These results are further discussed in the context of specific bonding configurations of the cations (Si and Y) with the anions (O and N) and their implications on the metal-containing intergranular glassy films in polycrystalline Si 3 N 4 .

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High-resolution silicon-29 nuclear magnetic resonance in the Y-Si-O-N system

Cited by 68 publications

References 0 publications

Revisiting Y2Si2O7 and Y2SiO5 polymorphic structures by 89Y MAS-NMR spectroscopy

Revisiting Y2Si2O7 and Y2SiO5 polymorphic structures by 89Y MAS-NMR spectroscopy

Synthesis of a Novel Polyethoxysilsesquiazane and Thermal Conversion into Ternary Silicon Oxynitride Ceramics with Enhanced Thermal Stability

Electronic structure and bonding in the Y-Si-O-N quaternary crystals

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