Evidence for the formation of SiON glasses

Kohn, Simon C.; Hoffbauer, Wilfried; Jansen, Martin; Franke, R.; Bender, S.

doi:10.1016/s0022-3093(97)00467-5

Cited by 46 publications

(40 citation statements)

References 22 publications

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“…Significant experimental results for the identification and differentiation of the SiO (4Àx) N x tetrahedra (0 x 4) might also be available from 29 Si and 15 N MAS NMR investigations. [14,29] …”

Section: Methodsmentioning

confidence: 99%

“…[11] These compounds may be viewed as a link between oxidic silicates and aluminosilicates on one hand and the nitridosilicates and nitridoaluminosilicates on the other. [12,13] Among the hitherto known crystalline nitridosilicates, [10] oxonitridosilicates, and oxonitridoaluminosilicates [11±13] as well as all the glassy phases that have been investigated in the systems Si-O-N and Si-Al-O-N [11,14] no experimental evidence for the occurence of octahedrally coordinated silicon has yet been found.…”

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confidence: 99%

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Ce16Si15O6N32—An Oxonitridosilicate with Silicon Octahedrally Coordinated by Nitrogen

Köllisch¹,

Schnick²

1999

Angew. Chem. Int. Ed.

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A rarity in solid-state chemistry is octahedrally coordinated silicon. Ce Si O N is the first nitridosilicate with this structural motif. Most oxosilicates containing octahedrally coordinated silicon are high-pressure phases. In contrast to that Ce Si O N has been synthesized under ambient pressure. An SiN octahedron that is surrounded by two parallel rings formed from six Si(O,N) tetrahedra is depicted.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Ce16Si15O6N32—An Oxonitridosilicate with Silicon Octahedrally Coordinated by Nitrogen

Köllisch¹,

Schnick²

1999

Angew. Chem. Int. Ed.

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“…[9,13] According to the calculations of the Madelung part of the lattice energy (MAPLE) [14] in Ca[Si 2 O 2 N 2 ] a complete O/N-ordering seems to be very likely. Accordingly, the O atoms are bonded terminally to the Si atoms (O [1] ), and each N atom links three Si atoms within the layers (N [3] ).…”

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confidence: 99%

Ca[Si₂O₂N₂]—A Novel Layer Silicate

et al. 2004

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Dedicated to Professor Martin Jansen on the occasion of his 60th birthdaySilicates are one of the largest classes of compounds in inorganic chemistry.[1] Most of them are pure oxidic compounds (oxosilicates). SiX 4 tetrahedrons (X = O, N) are a typical feature of almost all previously described oxo-and nitridosilicates.[2] They are connected through common corners (X = O, N) or edges (X = N) and form condensed anionic structures with a wide range of degree of condensation. [1, 3] The degree of condensation k (i.e. the molar ratio Si/X) of oxosilicates, which can easily be derived from the empirical formula, usually allows a conclusion to be drawn about the dimensionality of the framework of simple oxosilicates: Nesosilicates such as almandine (Fe 3 [3] and silicon nitride Si 3 N 4 itself, degrees of condensation have been observed even within the range 1 = 2 < k < 3 = 4 , which are not accessible in oxosilicates. During the last few years we have conducted a systematic investigation of new oxonitridosilicates (sions) and oxonitridoaluminosilicates (sialons).[9] Both classes are of considerable significance in materials science due to their extraordinary chemical and thermal stability, and they are of special interest to us as host lattices for rare-earth-doped phosphors. [10] In the system CaO-SiO 2 -Si 3 N 4 we recently discovered Ca[Si 2 O 2 N 2 ], which was obtained by facile reaction of CaCO 3 with Si 3 N 4 at 1580 8C in a radio frequency (r. f.) furnace as colorless lath-shaped single crystals (see Experimental Section). The single-crystal X-ray structure analysis [11] of the oxonitridosilicate Ca[Si 2 O 2 N 2 ] revealed an unexpected structure: According to the empirical formula and the respective degree of condensation of k = 2À originates from the fact that in this compound every N atom-unlike the O atoms in oxosilicates [1]

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“…A tendency of the materials to partially crystallize was observed for samples with Ca and N contents higher than 50 and 70 e/o, respectively. In view of a report of a binary Si 3 N 4 ±SiO 2 glass, obtained by quenching a melt from 1850 C, [18] it is likely that the vitreous zone boundaries in the present system are not only dependent on composition but also on preparation temperature and quench rate, the former being restricted by the dissociation of SiO 2 and Si 3 N 4 at higher temperatures.[18±20] The variation of T g and crystallization temperature, T c , with nitrogen content is shown COMMUNICATIONS …”

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confidence: 99%

“…The width of the main peak is less than half of the corresponding widths for oxosilicate and previously reported oxynitride glasses. [18] High-resolution electron microscopy (HREM) images (Fig. 3) also reveal some local ordering.…”

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Silicate Glasses with Unprecedented High Nitrogen and Electropositive Metal Contents Obtained by Using Metals as Precursors

et al. 2005

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A novel glass-synthesis route involving the reaction of electropositive elements in their metallic state with Si 3 N 4 and SiO 2 in N 2 atmosphere is presented. New silicate glass compositions have been obtained in this way with nitrogen contents higher than 70 e/o (N content in equivalents; e = [N]/ 3[N] + 2 [O], where [N] and [O] are the atomic concentrations of N and O, respectively), compared to previously reported oxynitride glasses typically that have concentrations below 30 e/o. [1][2][3][4][5][6][7][8] The new glasses constitute a significant extension of silicate glass compositions and also show high chemical flexibility. Samples have been prepared with high concentrations of alkaline-earth and rare-earth elements such as Ca, Sr, Ba, La, Pr, and Sm (higher than 50 % cations; hereafter cation %). The glasses can easily be obtained in macroscopic quantities. They demonstrate high refractive indices, up to 2.30, and Vickers hardness values up to 13.3 GPa, which are the highest values reported for any silicate glass. The technological use of silicate glasses constitutes an important part of modern civilization. They have, however, inherent compositional limitations that inhibit further improvements of their various properties, e.g., the attainable amount of network-modifier elements (Na, Ca, Ba, etc.) is rather small and restricted by the Si/O ratio. One way of increasing the amount of electropositive elements in silicates is to substitute oxygen with nitrogen. Such oxonitridosilicates do not occur in nature and investigations of them originated from efforts to prepare new Si 3 N 4 -based ceramic materials with improved mechanical properties, i.e. sialons.[1±4] Sialon and oxonitridosilicate crystal chemistries are similar to that of oxosilicates, but differ in that nitrogen, unlike oxygen, may bond to three or even four Si atoms, [5,6] resulting in higher connectivity and condensation of the networks. Due to the high formal charge of ±3 for nitrogen, more or higher valent cations can be incorporated in the phases for a given network connectivity. Studies of oxynitride glasses over the last few decades [7±14] have demonstrated that an increase in nitrogen content increases the glass-transition temperature, T g , viscosity, elastic modulus, hardness, and refractive index. [6,15±17] This can be partly attributed to a higher crosslinking of the Si(Al) network. Increased nitrogen contents have been desired by both academic and industrial sectors to improve physical properties, but efforts so far have had limited success. The glass modifiers have mainly been added as oxides, [1±7] typically leading to nitrogen contents less than 30 e/o. In the synthesis method presented here, rare-earth and/or alkaline-earth elements are introduced instead as metals. Precursor mixtures of electropositive elements, Si 3 N 4 , and SiO 2 , are ground in an oxygen-and water-free atmosphere and then heat treated, using graphite or radiofrequency furnaces, at 1500±1800 C in N 2 atmosphere, which serves as the nitridation source f...

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Evidence for the formation of SiON glasses

Cited by 46 publications

References 22 publications

Ce16Si15O6N32—An Oxonitridosilicate with Silicon Octahedrally Coordinated by Nitrogen

Ce16Si15O6N32—An Oxonitridosilicate with Silicon Octahedrally Coordinated by Nitrogen

Ca[Si₂O₂N₂]—A Novel Layer Silicate

Silicate Glasses with Unprecedented High Nitrogen and Electropositive Metal Contents Obtained by Using Metals as Precursors

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Evidence for the formation of SiON glasses

Cited by 46 publications

References 22 publications

Ce16Si15O6N32—An Oxonitridosilicate with Silicon Octahedrally Coordinated by Nitrogen

Ce16Si15O6N32—An Oxonitridosilicate with Silicon Octahedrally Coordinated by Nitrogen

Ca[Si2O2N2]—A Novel Layer Silicate

Silicate Glasses with Unprecedented High Nitrogen and Electropositive Metal Contents Obtained by Using Metals as Precursors

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Ca[Si₂O₂N₂]—A Novel Layer Silicate