Nanocluster-containing mesoporous magnetoceramics from hyperbranched organometallic polymer precursors

被引:135
作者
Sun, QH
Lam, JWY
Xu, KT
Xu, HY
Cha, JAK
Wong, PCL
Wen, GH
Zhang, XX
Jing, XB
Wang, FS
Tang, BZ [1 ]
机构
[1] Hong Kong Univ Sci & Technol, Mat Characterizat & Preparat Facil, Dept Chem, Kowloon, Hong Kong, Peoples R China
[2] Hong Kong Univ Sci & Technol, Dept Phys, Kowloon, Hong Kong, Peoples R China
[3] Chinese Acad Sci, Changchun Inst Appl Chem, Changchun 130022, Peoples R China
关键词
D O I
10.1021/cm000094b
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Pyrolysis of hyperbranched poly[1,1'-ferrocenylene(methyl)silyne] (5) yields mesoporous, conductive, and magnetic ceramics (6). Sintering at high temperatures (1000-1200 degrees C) under nitrogen and argon converts 5 to 6N and 6A, respectively, in similar to 48-62% yields. The ceramization yields of 5 are higher than that (similar to 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 alpha-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 similar to 49 emu/g) and near-zero remanence and coercivity; that is, 6A is an excellent soft ferromagnetic material with an extremely low hysteresis loss.
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页码:2617 / 2624
页数:8
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