Size-tunable synthesis of iron oxide nanocrystals by continuous seed-mediated growth: role of alkylamine species in the stepwise thermal decomposition of iron(II) oxalate

Ryosuke Nozawa; Takashi Naka; Masato Kurihara; Takanari Togashi

doi:10.1039/d1dt02953c

Size-tunable synthesis of iron oxide nanocrystals by continuous seed-mediated growth: role of alkylamine species in the stepwise thermal decomposition of iron(II) oxalate

Dalton Trans. 2021 Nov 16;50(44):16021-16029. doi: 10.1039/d1dt02953c.

Authors

Ryosuke Nozawa¹, Takashi Naka², Masato Kurihara¹, Takanari Togashi¹

Affiliations

¹ Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan.
² National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan. togashi@sci.kj.yamagata-u.ac.jp.

PMID: 34613325
DOI: 10.1039/d1dt02953c

Abstract

The properties of inorganic nanoparticles (NPs) are governed by their size. Therefore, tuning the size of NPs is a fundamental technique in nanoscience. However, the size-tunable synthesis of inorganic NPs is generally carried out in a dilute solution, which produces large quantities of waste. Herein, we report the predictable size-tunable synthesis of Fe₃O₄ NPs by the stepwise thermal decomposition of iron(II) oxalate (Fe(ox)). Monodisperse Fe₃O₄ seed crystals were synthesized by the thermal decomposition of oleylamine-coordinated iron oxalate (Fe(ox)-OAm) in a small amount of oleylamine, followed by continuous seed-mediated growth of Fe₃O₄ NPs. The thermal decomposition behavior of Fe(ox) in oleylamine with and without N,N-diethyl-1,3-diaminopropane (dedap) revealed the important role of dedap in the stepwise thermal decomposition of Fe(ox). The size of the Fe₃O₄ NPs was easily tuned via the stepwise thermal decomposition of Fe(ox) by controlling the amount of decomposed Fe(ox) in a small amount of an alkylamine mixture. The particle diameter was predicted from the size of the Fe₃O₄ seed crystals and the amount of decomposed Fe(ox). Finally, the size dependency of magnetic properties of the synthesized Fe₃O₄ NPs was studied. This continuous seed-mediated growth method based on the stepwise thermal decomposition of metal oxalate can be applied to control the size of a variety of metal and metal oxide NPs.