Synthesis of an extremely stable ceramic in the system Si/B/C/N using 1-(trichlorosilyl)-1-(dichloroboryl)ethane as a single-source precursor

Abstract

A new material discovered in the Si/B/C/N system was found to remain in the amorphous state up to a very high temperature of 2000°C. This material, with the composition Si2B2N5C4, is the only material in this system which does not undergo any microstructural changes until such high temperatures. Furthermore, the substance shows an extremely high resistance to oxidation up to 1500°C. The synthesis of amorphous Si2B2N5C4 was achieved by using the novel single-source precursor 1-(trichlorosilyl)-1-(dichloroboryl)ethane (TSDE), which can be synthesized in high yields from inexpensive starting materials in a simple single pot reaction. Examination of the structural properties of the pyrolytic ceramic reveals a substructure consisting of tetrahedrally and trigonally-planar coordinated silicon and boron, respectively. Si-C- and B-C-bonds present in the molecular precursor could not be distinguished from SiN- and B-N-bonds in the fully pyrolized ceramic. EDX and X-ray-diffraction showed the material to have a homogeneous elemental distribution, and no phase separation could be detected.