Synthesis of SiFeC Magnetoceramics from Reverse Polycarbosilane‐Based Microemulsions

Abstract

In this paper, we report the synthesis of iron‐containing SiC(O) magnetoceramics using a reverse microemulsion technique. First, an aqueous iron nitrate solution as the internal phase and a polycarbosilane (PCS)–heptane solution as the continuous phase were emulsified in the presence of a surfactant to synthesize iron‐containing PCS (Fe‐PCS) reverse microemulsion systems. After the removal of water and heptanes, the Fe‐PCS precursors were pyrolyzed at 600°–1200°C to produce magnetoceramics. The structures and magnetic properties of the ceramics obtained were characterized by using X‐ray diffraction, transmission electron microscopy, electron probe microanalysis, and superconducting quantum interference device. The results showed that the ceramics contained Fe3Si nanoparticles, which dispersed in SiCO amorphous matrix. This unique structure makes the ceramics excellent soft ferromagnetic materials with a high magnetizability and negligibe hysteresis loops.

Magnetoceramics from the Bulk Pyrolysis of Polysilazane Cross-Linked by Polyferrocenylcarbosilanes with Hyperbranched Topology

“…From the TEM morphology (Figures 4e,f), homogeneous nanostructures can be observed, which are different from the heterogeneous morphology with dispersed iron-based particle grains in the ceramic matrix prepared using inorganic compounds. 23,24 The XPS and EDS analyses show the existence of silicon, iron, carbon, nitrogen, and oxygen elements in the ceramics (Figures 5 and S5). The atomic composition and ceramic formula for C0−C4 are described in Table 1.…”

“…The first way to prepare such ceramics is by blending the precursor with a metal or metal-oxide powder. A liquid polysilazane had been previously demonstrated to be mixed with iron or iron carbonyl, 20 Fe 3 O 4 , 21 FeCl 2 , 22 FeCl 3 , 23 Fe(NO 3 ) 3 , 24 and ferrocene, 25 respectively. The subsequent pyrolysis up to 1000−1100 °C, in a nitrogen atmosphere, leads to the formation of Si−Fe−C−N magnetic materials with a potential for application in harsh environments.…”

“…However, this method is limited by the particle size of the metal (oxide) powders. At the same time, a heterogeneous morphology with dispersed iron-based particle grains (α-Fe, Fe 3 C, or Fe 3 Si) is usually observed in the ceramic matrix because inorganic powders are insoluble with the organic precursors. − …”

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

“…One convenient access to iron silicide-based ceramic nanocomposites involves the use of polymeric precursors which are modified with suitable iron-containing compounds prior to their conversion into the ceramics (see Table 1 ). In the case of polycarbosilane-derived ceramic composites, the pyrolysis of iron nitrate- [ 358 ] or acetylacetonate-modified precursors [ 359 ] leads to iron silicide-based ceramic composites, whereas an iron carbonyl-modified polycarbosilane was shown to convert into Fe/SiC ceramic nanocomposite [ 360 ].…”

Polymer derived non-oxide ceramics modified with late transition metals

“…19 Iron containing SiC(O) magnetoceramics were recently synthesized using iron nitrate and a polycarbosilane. 20 The Fe@PCS precursors were pyrolyzed at 600-1200 1C to produce magnetoceramics. The powder XRD and TEM analysis showed that the ceramics contained Fe 3 Si nanoparticles, which were dispersed in a amorphous SiC(O) matrix.…”