Crystallization Behavior of Amorphous Silicon Carbonitride Ceramics Derived from Organometallic Precursors

The crystallization behavior of organometallic‐precursor‐derived amorphous Si‐C‐N ceramics was investigated under N 2 atmosphere using X‐ray diffractometry (XRD), transmission electron microscopy (TEM), and solid‐state 29 Si nuclear magnetic resonance (NMR) spectroscopy. Amorphous Si‐C‐N ceramics with a C/Si atomic ratio in the range of 0.34–1.13 were prepared using polycarbosilane‐polysilazane blends, single‐source polysilazanes, and single‐source polysilylcarbodiimides. The XRD study indicated that the crystallization temperature of Si 3 N 4 increased consistently with the C/Si atomic ratio and reached 1500°C at C/Si atomic ratios ranging from 0.53 to 1.13. This temperature was 300°C higher than that of the carbon‐free amorphous Si‐N material. In contrast, the SiC crystallization temperature showed no clear relation with the C/Si atomic ratio. The TEM and NMR analyses revealed that the crystallization of amorphous Si‐C‐N was governed by carbon content, chemical homogeneity, and molecular structure of the amorphous Si‐C‐N network.