Preparation and magnetic properties of Fe/Si/C/N ceramics derived from a polymeric precursor

Iron-containing polysilazanes (PSZI) were prepared by the amine displacement reaction along with heat-induced vinyl crosslinking reactions between Fe[N(SiMe(2)Vi)(2)](3) (Vi = -CH=CH2) and polysilazane containing -Si-Vi (PVSZ). The PSZIs were converted into magnetic ceramics by the pyrolysis in N-2. The ceramics produced were investigated by X-ray diffraction, transmission electron microscope and vibrating sample magnetometer at room temperature. It was indicated that alpha-Fe is the only magnetic crystalline embedded in the amorphous Si/C/N-based matrix from 500 to 900 degrees C. Moreover, the sample prepared at 500 degrees C showed few hysteresis at room temperature, consistent with the behavior of superparamagnetic particles, which was confirmed by the zero-field-cooled and field-cooled magnetization measurement. Additionally, the results indicated that the magnetic properties of the ceramics could be tuned by controlling the content of iron and the pyrolysis temperature. This flexibility may be advantageous for some particular magnetic materials applications. (c) 2007 Wiley Periodicals, Inc.