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

ϵ-Fe2O3, a metastable phase of iron oxide, is widely known as a room-temperature 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+

DOI

10.1021/acs.inorgchem.9b03302

Citation

Yasuhara , S , Hamasaki , Y , Katayama , T , Ao , T , Inaguma , Y , Hojo , H , Karppinen , M , Philip , A , Yasui , S & Itoh , M 2020 , ' Modulating the Structure and Magnetic Properties of ϵ-Fe 2 O 3 Nanoparticles via Electrochemical Li + Insertion ' , Inorganic Chemistry , vol. 59 , no. 7 , pp. 4357–4365 . https://doi.org/10.1021/acs.inorgchem.9b03302

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202103102232

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[article-cris] Kemian tekniikan korkeakoulu / CHEM

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