シリカ層で被覆されたマグネタイトナノ粒子の還元(薄膜・微粒子・多層膜・人工格子)

概要

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Metallic iron (Fe) nanoparticles have been synthesized by reducing SiO_2-coated magnetite (Fe_3O_4) nanoparticles. The Fe_3O_4 nanoparticles with an average diameter of about 10 nm were prepared by thermal decomposition of the iron-oleate complex, and were subsequently coated with SiO_2. The SiC_2-coated Fe_3O_4 nanoparticles were annealed at various temperatures for 2 hr in flowing H_2 gas to convert them to Fe nanoparticles. The Fe_3O_4 nanoparticles with 3- and 5-nm SiO_2 coatings were completely reduced to Fe nanoparticles at 800℃. However, under these conditions, coalescence of thus-formed Fe nanoparticles was also observed. The Mossbauer spectrum of the Fe nanoparticles prepared by annealing at 800℃ revealed that about 84% of the nanoparticles were ferromagnetic α-Fe at room temperature. Approximately 16% of the Fe nanoparticles were paramagnetic due to superparamagnetic-like behavior at room temperature.
社団法人日本磁気学会の論文
2008-05-01