Synthesis and characterization of new amorphous Si/B/N/C ceramics with increased carbon content through single-source precursors

New molecular single-source precursors for the preparation of carbon-rich random inorganic networks in the quaternary system Si/B/N/C have been synthesized and fully characterized by spectroscopic methods (infrared, nuclear magnetic resonance and mass spectrometry). As a new structural feature, the precursors contain a methylene bridge between silicon and boron leading to an efficient incorporation of carbon into the random network. Cross linking of the single-source precursors Cl 3 Si–CH 2 –BCl 2 (trichlorosilyl dichloroboryl methane) and (CH 3 )Cl 2 Si–CH 2 –BCl 2 (dichlorosilyl dichloroboryl methane) with methylamine and subsequent pyrolysis of the resultant preceramic polymers at 1500 °C in an inert gas atmosphere yield the amorphous ceramics Si 3 B 3 N 7 C 5 and Si 3 B 3 N 5 C 7 , respectively. Both compositions exhibit high-temperature stability with only low mass losses at heating them to 2000 °C and, at the same time, they show a remarkable resistance against oxidation in pure oxygen at least up to 1300 °C.