Microwave-induced crystallization of polysilazane-derived silicon carbonitride

An amorphous covalent silicon-, carbon- and nitrogen-containing solid is prepared by the thermolysis of a polyvinylsilazane. Crystallization of the metastable material is induced by subsequent heat treatment at 1600 degreesC. For that purpose, microwave and conventional heating are applied and compared. The resulting materials are investigated by conventional and analytical transmission electron microscopy and X-ray diffraction. In the case of the conventionally heated material, thermal degradation occurs accompanied by a strong reduction of the nitrogen content. In contrast, kinetic stabilization of the Si-C-N solid by microwave heating is observed. Based on thermodynamic considerations, a model for the high-temperature behavior of the material is presented.