writer：J. Kong, T. Schmalz, G. Motz, A. H.E. Müller
keywords：Hyperbranched Poly(ferrocenyl)borocarbosilanes
source：期刊
specific source：J. Mater. Chem. C, 2013, 1: 1507-1514
Issue time：2013年
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 mm 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.