A new strategy to prepare magnetoceramics by bulk pyrolysis of Fe-containing polyamide precursors

Abstract

In this work, a new strategy was developed to prepare magnetoceramics through a bulk pyrolysis of novel Fe-containing polyamide preceramic precursors at low pyrolysis temperature. A series of novel polyamides with different chemical structures were synthesized by bulk Michael addition and polycondensation, and their structures were characterized. Polymer precursors (PPs) were prepared by direct melt blending polyamides and FeCl3, and polymer-derived ceramics (PDCs) were prepared via the pyrolysis of PPs. The polyamide structure with pendant pyridine groups in repeating units makes the Fe complexes uniformly dispersed in matrix. The relationship between magnetoceramic compositions and PP structures was investigated by TGA, XPS, XRD, FE-SEM, FE-TEM and VSM characterizations. Different chemical structures and Fe catalysis effect lead to different thermal decomposition processes of PPs. Increasing crystal-Fe content in PDCs contributes to higher magnetic properties. The morphology of crystal phases in PDCs relies on the structures of PPs and pyrolysis temperature. Different pyrolysis temperatures and chemical structures of PPs bring about different Fe crystal phases and carbon crystal state of nanosheets or nanofiber bundles.