Processing and magnetic properties of metal-containing SiCN ceramic micro- and nano-composites

Owing to their excellent high temperature and oxidation resistance, non-oxide polymer-derived silicon-based ceramics are suitable for applications in hot and corrosive environments. The metal (Fe, Co)-containing pre-ceramic compounds combine the processability of organic polymers with the physical and chemical characteristics of the metallic component. In this study, we will introduce two different routes to embed metal particles in a SiCN ceramic matrix, derived from the commercially available polysilazane Ceraset®. (1). Mixing and milling of metal powders (Fe, Co) with pre-crosslinked polysilazane followed by pyrolysis at 1100 °C. (2). Chemical reaction between metal carbonyl compounds, namely Fe(CO)5 and Co2(CO)8, with pure polyorganosilazane followed by pyrolysis at 1100 °C. Both synthetic routes will be discussed on two particular examples, iron- and cobalt-containing samples as well as their resulting different microstructures with respect to their magnetic properties. The phases and microstructures of the metal–SiCN composites were investigated in terms of X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDX, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and magnetometer. Upon annealing in argon at 1100 °C, the crosslinked polysilazane blended with iron powder possesses a high saturation magnetization of about ∼57 emu/g and exhibits good ferromagnetic behaviour in comparison to the one blended with cobalt. The magnetic measurements were performed within the temperature range 65–300 K.