Nanostructured magnetoceramics from hyperbranched polymer precursors

Controlled pyrolysis of a hyperbranched polysilyne, poly[1, 1 ' -ferrocenyl ene(methyl)silyne] (1), at high temperature in inert atmosphere produces no nostructured ceramics (2) in similar to 48-62% yields. The ceramic products 2 are characterized by SEM. XPS, EDX, XRD, and SQUID. It is found that the ceramics are electrically conductive and possess a mesoporous architecture . The iron contents of 2 estimated by EDX are 36-43%. The nanocrystals form ed in the ceramics produced under nitrogen 2N are mainly alpha -Fe2O3 where as those in the ceramics produced under argon 2A are mainly Fe3Si. When mag netized by an external field at room temperature. 2A exhibits a high satura tion magnetization (M-s similar to 49 emu/g) and near-zero remanence and co ercivity. (C) 2001 Elsevier Science BN. All rights reserved.