Magnetoceramic nanocrystals from the bulk pyrolysis of novel hyperbranched polyferrocenyl(boro)carbosilanes
Magnetoceramic nanocrystals from the bulk pyrolysis of novel hyperbranched polyferrocenyl(boro)carbosilanes
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DOI：
10.1039/c2tc00193d
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发表时间：
2013-01
影响因子：
6.4
通讯作者：
Jie Kong;T. Schmalz;G. Motz;A. Müller
中科院分区：
文献类型：
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作者：
Jie Kong;T. Schmalz;G. Motz;A. Müller
我们报道了一种新的策略，通过直接热解超支化聚碳硅烷来合成纳米结构磁陶瓷，而不需要任何纳米级模板的辅助。采用方便的A2+B3策略合成了超支化聚二茂铁基(BO)碳硅烷(HB-PBCS)。HB-PBCS在1100℃氮气气氛下热解后，生成了晶粒度为20~60 nm的硅化铁纳米晶富集型陶瓷。聚合物前驱体的规整结构和相当高的陶瓷产率在保留铁和硅方面优于线性前驱体，这些铁和硅在本体热解过程中有可能聚集成规则的纳米晶。此外，如果采用具有规则结构的HB-PBCS和高陶瓷产率的硅烯-二乙炔聚合物的混合前驱体，在相同的热解条件下，可以得到直径为20-30 nm、长径比为∼5的均匀纳米棒和直径为4-8μm的微球的分级结构。振动样品磁强计测量表明，所制备的硅化铁纳米晶富集陶瓷具有较弱的铁磁性，具有超低的磁滞损耗。
We report a novel strategy to synthesize nanostructured magnetoceramics via a direct bulk pyrolysis of hyperbranched polycarbosilanes without any assistance of nanoscaled templates. The hyperbranched polyferrocenyl(boro)carbosilanes (hb-PBCS) were synthesized via a convenient A2+B3 strategy. After the pyrolysis of hb-PBCS under a nitrogen atmosphere at 1100 °C, iron silicide nanocrystal enriched ceramics with a grain size of 20–60 nm were formed. The regular architecture and quite higher ceramic yield of polymeric precursors are superior in retaining iron and silicon that give a possibility to aggregate into regular nanocrystals during the bulk pyrolysis in comparison to their linear counterparts. Furthermore, if the mixed precursor of hb-PBCS with regular architecture and a silylene-diacetylene polymer with high ceramic yield was employed, a hierarchical structure of uniform nanorods with diameters of 20–30 nm and aspect ratios of ∼5 together with microspheres with diameters of 4–8 μm could be obtained under the same pyrolytic conditions. A vibrating sample magnetometer measurement demonstrated that the generated iron silicide nanocrystal enriched ceramics possessed weak ferromagnetism with an ultralow hysteresis loss.