Novel binary and ternary phases in the Si-C-N system

The present article reviews recent advances in synthesis of novel phases in the ternary Si-C-N system. A dense carbon nitride phase, C₂N₂(NH), was synthesized for the first time at high pressures and high temperatures in a laser heated diamond anvil cell (LH-DAC). Based on results of electron diffraction, EELS- and SIMS-measurements combined with theoretical calculations the structure of this new C-N-H compound was analysed to be a defect wurtzite structure of the sinoite (Si₂N₂O)-type. Farther, a variety of amorphous SiCN phases and the first ternary crystalline phases, namely Si(NCN)₂ and Si₂N₂(NCN), were synthesized at ambient pressure. In general, the high-pressure polymorphs of Si-C-N materials are predicted to exhibit a unique combination of high hardness, thermal stability and oxidation resistance with interesting optoelectronic properties.