Magnetoceramic nanocrystals from the bulk pyrolysis of novel hyperbranched polyferrocenyl(boro)carbosilanes

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Kong, Jie ; Schmalz, Thomas ; Motz, Günter ; Müller, Axel H. E.:
Magnetoceramic nanocrystals from the bulk pyrolysis of novel hyperbranched polyferrocenyl(boro)carbosilanes.
In: Journal of Materials Chemistry C. Bd. 1 (2013) Heft 7 . - S. 1507-1514.
ISSN 2050-7534
DOI: https://doi.org/10.1039/C2TC00193D

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Abstract

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.