The Si-C-N System

FIGURE 18.5 Si-C-N phase diagram. A ((3-SiC2N4) andB (Si2CN4) are the first crystalline ternary phases in the Si-C-N system. They were discovered by in situ x-ray diffraction during heating of [Si(NCN)2] at -400 and 920°C, respectively. ... 

Numerous thermodynamic calculations of phase equilibria in the Si-C-N system have been published but only few experimental investigations are documented. Calculated isothermal sections [117, 234-237], isopleths [117, 234], different types of potential phase diagrams [234,235,238-244] and phase fraction diagrams [234, 239] were presented. Additional information is provided by [245]. No or very low solid solubilities between SiC and Si3N4 could be detected by X-ray diffraction up to 2500 K [246, 247]. Also the nitrogen solubility in SiC is low. For more experimental information see [248, 249]. 

The Si-C-N system was calculated thermodynamically by extrapolations from the datasets for the binary subsystems. The ternary phases Si2CN4 and jS-SiC2N4 [21] are not stable at T > 1273 K and were not taken into account for... 

A Scheil reaction scheme was given by [117] and later modified with regard to the reaction temperatures by [234]. The Scheil reaction scheme for the Si-C-N system (valid for P = 1 bar) is shown in Fig. 18. Three degenerated reactions and one transition reaction occur. The reactions (1) and (2)... 

Fig. 18. Scheil reaction scheme for the Si-C-N system (/i-SiC/a-SiC and a-Si3N4/jS-Si3N4 transformations not indicated) [234]...

Fig. 19. Calculated phase fraction diagrams in the Si-C-N system for PHMS-derived ceramics (C Si < 1) [234, 237]...

Finally, ceramic composites belonging to the ternary Si—C—N system are of high technical relevance. Crystalline solids of composition SiQN,25 have a polymeric network structure they are made according to ... 

Fig. 23. Phase relations in the Si-C-N-O system as a function of oxygen partial pressure and temperature at ac = 1 and nitrogen pressure equal to 1 and 10 atm. After Wada et at. [128], Reproduced with permission of the American Ceramic Society, Westerville.

G. Chollon, Oxidation behavior of ceramic fibers from the SI-C-N-0 system and subsystems. Key Engineering Materials, 164/165,395-398(1969). 

Chollon, G. (2000). Oxidation behaviour of ceramic fibres from the Si-C-N-0 system and related snb-systems. Journal of the European Ceramic Society, 20(12), 1959-1974. doi 10.1016/S0955-2219(00)00101-l. 

Riedel, R., Greiner, A., Miehe, G., Dressier, W., Fuess, H., Bill, ., Aldinger, F. (1997). The first crystalline solids in the ternary Si-C-N system. Angewandte Chemie International Edition in English, 36(6), 603-606. doi 10.1002/anie. 199706031. 

Jansen M, Jaschke B, Jaschke X (2002) Amorphous Multinary Ceramics in the Si-B-N-C System. 101 137-192... 

Schulz S (2002) Synthesis, Structure and Reactivity of Group 13/15 Compounds Containing the Heavier Elements of Group 15, Sb and Bi 103 117-166 Seifert HJ, Aldinger F (2002) Phase Equilibria in the Si-B-C-N System. 101 1-58 Stahlke D, see Mahalakshmi L (2002) 103 85-116... 

The preparation of silyl derivatives with a Si—C bond between the silicon atom and the drug is not so easy to realize as compared with Si—O and Si—N systems. In most cases the Si-C bond must be constructed at the beginning of synthesis. This is shown for the triethylsilyl derivative (4) of phenethylamine (3) in Scheme 1 ... 

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