Facile fabrication of Fe-doped Si–C–N ceramic microspheres with flower-like morphology and the infrared extinction property.

Nonoxide ceramics microspheres with multiple compositions are attractive for wide applications especially in thermal insulation science. The flower-like Fe-doped Si–C–N ceramic microspheres with the average size of about 1 μm were fabricated from polyvinylsilazane and ferrocene precursor through polymer-derived ceramics technology combined with emulsion polymerization method. The properties of the resultant microspheres were characterized by FTIR, SEM-EDX, VSM, TGA, and XRD. The morphology and size of the microspheres could be tuned by changing of ferrocene content, cross-linking time, and pyrolysis temperature. The ceramic microspheres were estimated to be composed of SiC/Si₃N₄ and α-Fe/Fe₂O₃ crystal phase, and the folding sheets on the surface induced the flower-like morphology due to phase separation and crystal rearrangement. The effective extinction coefficient of silica aerogels opacified with 10 wt% of Fe-doped Si–C–N microspheres increased with rising pyrolysis temperature, the maximum value of e* reached 27.5 cm²/g at 1300 °C. Moreover, the microspheres showed weak room temperatures ferromagnetism, which was facilitated to alignment in fabrication and recycle, make them an ideal candidate for aerogels in infrared shielding application. Highlights: Novel Fe-doped Si-C-N ceramic microspheres with flower-like morphology were prepared by polymer-derived ceramics technology combined with the emulsion polymerization method. The morphology and size of microspheres could be tuned by changing conditions. Microspheres were composed of multiple crystals. Microspheres showed weak room temperature ferromagnetism. [ABSTRACT FROM AUTHOR]