Nanodomain growth in amorphous Si–C–N

Polymer‐derived amorphous Si–C–N ceramics are phase separated into amorphous nanodomains after thermolysis. These nanodomains are expected to have a crucial importance for the extraordinary high temperature stability of these materials. We investigated nanodomain growth during isothermal annealing at 1400 °C using small angle X‐ray scattering. The as‐thermolyzed sample shows a domain radius of about 5 Å as determined from Guinier plots. During annealing, fast nanodomain growth up to 9 Å is observed for times up to 30 h while for longer annealing times up to 165 h the growth considerably slows down, resulting in a domain size of 11 Å. The experimental data can be fitted by a model based on diffusion controlled domain growth and simultaneous slow‐down of diffusion due to structural relaxation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)