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Abstract: Iron sulfide nanocomposites have been prepared through reactions of bis[bis(trimethylsilyl)amido]iron(II) or zerovalent iron nanoparticles (NPs) with hydrogen sulfide gas. The chemical composition of these materials was analyzed by TEM, XRD, WAXS and Mössbauer measurements. Decomposition of bis[bis(trimethylsilyl)amido]iron(II) under an H2S atmosphere in the presence of palmitic acid produces thin iron sulfide nanoflakes, which seemingly consist of Fe2S2 and Fe7S8. The sulfidation of 9 nm zerovalent iron NPs with H2S yields thin nano flakes exhibiting the same iron sulfide phases and residual iron. Remarkably, treatment of slightly larger iron NPs (13 nm) with H2S (or alternatively benzylthiol) yields well‐shaped iron–iron sulfide core‐shell particles. These particles exhibit a crystalline iron core and an amorphous iron sulfide shell, which likely consists of Fe2S2, Fe7S8 and Fe1−XS. Magnetic measurements on these core‐shell particles show a decrease of the total magnetization (compared to bulk iron) coming along with the sulfidation process. Owing to the partially preserved ferromagnetic character these iron–iron sulfide core‐shell particles were found to have magnetic heating properties. [ABSTRACT FROM AUTHOR]

Pure and highly crystalline γ-Fe2O3 nanocrystals (NCs) are obtained when hydrolysis and oxidation of a FeII organometallic precursor are performed in successive steps. Their synthesis in pure alkylamine leads to NCs of about 6 nm. In aqueous solutions of poly(vinyl)pyrrolidone, such pristine NCs form aggregates of about 150 nm that exhibit a high transversal relaxivity (r2=466 mm-1 s-1) about four times higher than that of a commercial Feridex magnetic resonance imaging (MRI) contrast agent. Consequently, they provide a significant decrease in the NMR signal at very short echo time (8 ms), which is of paramount importance in clinical practice because of the reduced duration of MRI measurements. [ABSTRACT FROM AUTHOR]