Solid‐state NMR and FT IR studies of the preparation of Si–B–C–N ceramics from ­boron‐modified polysilazanes

Abstract

N 4Àx units with x = 0, 1, 2). In addition, a considerable amount of hydrogen is present even at this temperature. The NMR studies have further shown that above 1700°C the amorphous ceramic demixes, along with the formation of crystalline silicon nitride and silicon carbide. Likewise, structural changes for BN domains have been registered that are attributed to the formation of turbostratic BN(C) interface layers. In summary, the present study has demonstrated that the combination of multinuclear solid-state NMR and FT IR spectroscopy is a powerful method to probe the thermolytic preparation of ternary and quaternary ceramic materials.

Silicon-Based Polymer-Derived Ceramics: Synthesis Properties and Applications-A Review

“…Because the thermal polymer to ceramic conversion involves a series of individual reaction steps that have to be considered carefully, [120][121][122][123] see also Chapter 3 of this review, the intention was to design precursors in a way that hydrogen alone is the only volatile thermolysis product Scheme 3. After subsequent cross-linking of the low viscosity polymers using nBuLi, the ceramization leads to SiCSi 3 N 4 ceramics without éfreeêcarbon.…”

“…[120][121][122][123] In particular, homogenisation and cross-linking are essential steps for the further processing of bulk PDCs.…”

Pyrolytic conversion of an AlSiNC precursor prepared via hydrosilylation between [Me(H)SiNH]4 and [HAlN(allyl)]m[HAlN(ethyl)]n

“…38,56 The formation of NH groups in an AE-alane moiety also appears to be possible via hydrogen abstraction of nitrogen radicals ( N · ), which forms via the homolytic cleavage of C-N bonds in the NCH 2 CH 3 groups. 57 Since a shoulder at −37 ppm, which is assignable to the N 3 SiC(sp 3 ) environment, 28,50 is observed in the solid-state 29 Si NMR spectrum of the residue Materials, Nanoscience and Catalysis pyrolyzed at 400…”

Precursor‐derived Si–(B–)C–N ceramics: thermolysis, amorphous state and crystallization

“…[72][73][74] Furthermore, these solids consist of CSi 4 units, as well as of sp 2 -hybridized carbon and boron-containing units, which is demonstrated by means of the 29 Si, 13 C and 11 B solid-state NMR spectra obtained for the PMBS-derived ceramic (Fig. 15).…”