We report on an alternative route to quaternary ceramics which can be
prepared by polycocondensation of commercially available polysilazanes with
the appropriate alkyl amides (M(NRR')X with M = B or P and
subsequent pyrolysis in argon atmosphere at 1000°C. Ceramic monoliths are
obtained if the modified polysilazane is crosslinked at 400°C for 3 h. After
ball-milling, sieving and cold isostatic pressing the green body is directly
pyrolysed to the appropriate monolith. The obtained material is amorphous to
X-ray-diffraction. Investigations by electron spectroscopie imaging (ESI) in
TEM indicate a homogeneous distribution of the elements M, Si, C and N (M =
B, P) within a resolution of 2 nm. Upon annealing at elevated tempertures in
a nitrogen atmosphere crystallization of the appropriate thermodynamically
stable phases occurs around 1400°C yielding a micro/nano-, nano/nano- or
micro/microcrystalline microstructure with design-tailored properties
depending on the element M.