Nanocluster-containing mesoporous magnetoceramics from hyperbranched organometallic polymer precursors

Q. Sun, J. W.Y. Lam, K. Xu, H. Xu, J. A.K. Cha, P. C.L. Wong, G. Wen, X. Zhang, X. Jing, F. Wang, B. Zhong Tang

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Abstract

Pyrolysis of hyperbranched poly[1,1'-ferrocenylene(methyl)silyne] (5) yields mesoporous, conductive, and magnetic ceramics (6). Sintering at high temperatures (1000-1200 °C) under nitrogen and argon converts 5 to 6N and 6A, respectively, in ~48-62% yields. The ceramization yields of 5 are higher than that (~36%) of its linear counterpart poly[1,1'-ferrocenylene(dimethyl)silylene] (1), revealing that the hyperbranched polymer is superior to the linear one as a ceramic precursor. The ceramic products 6 are characterized by SEM, XPS, EDX, XRD, and SQUID. It is found that the ceramics are electrically conductive and possess a mesoporous architecture constructed of tortuously interconnected nanoclusters. The iron contents of 6 estimated by EDX are 36-43%, much higher than that (11%) of the ceramic 2 prepared from the linear precursor 1. The nanocrystals in 6N are mainly α-Fe2O3 whereas those in 6A are mainly Fe3Si. When magnetized by an external field at room temperature, 6A exhibits a high-saturation magnetization (M(s) ~ 49 emu/g) and near-zero remanence and coercivity; that is, 6A is an excellent soft ferromagnetic material with an extremely low hysteresis loss.

Original languageEnglish (US)
Pages (from-to)2617-2624
Number of pages8
JournalChemistry of Materials
Volume12
Issue number9
DOIs
StatePublished - Jan 1 2000

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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