Modulating the Structure and Magnetic Properties of ϵ-Fe2O3 Nanoparticles via Electrochemical Li+ Insertion

Sou Yasuhara, Yosuke Hamasaki, Tsukasa Katayama, Takahiro Ao, Yoshiyuki Inaguma, Hajime Hojo, Maarit Karppinen, Anish Philip, Shintaro Yasui, Mitsuru Itoh

Research output: Contribution to journalArticlepeer-review

Abstract

ϵ-Fe2O3, a metastable phase of iron oxide, is widely known as a roomerature multiferroic material or as a superhard magnet. Element substitution into ϵ-Fe2O3 has been reported in the literature; however, the substituted ions have a strong site preference depending on their ionic radii and valence. In this study, in order to characterize the crystal structure and magnetic properties of ϵ-Fe2O3 in the Fe2+/Fe3+ coexisting states, Li+ was electrochemically inserted into ϵ-Fe2O3 to reduce Fe3+. The discharge and charge of Li+ into/from ϵ-Fe2O3 revealed that Li+ insertion was successful. X-ray magnetic circular dichroism results indicated that the reduced Fe did not exhibit site preference. Increasing the Li+ content in ϵ-Fe2O3 resulted in decreased saturation magnetization and irregular variation of the coercive field. We present a comprehensive discussion of how magnetic properties are modified with increasing Li+ content using transmission electron microscopy images and considering the Li+ diffusion coefficient. The results suggest that inserting Li+ into crystalline ϵ-Fe2O3 is a useful tool for characterizing crystal structure, lithiation limit, and magnetic properties in the coexistence of Fe2+/Fe3+

Original languageEnglish
Pages (from-to)4357-4365
Number of pages9
JournalInorganic chemistry
Volume59
Issue number7
DOIs
Publication statusPublished - Apr 6 2020

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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