Electrochemical Lithium Insertion of Iron Oxide Spinel Thin Films and Nanoparticles: Changes in Structure and Magnetic Properties

Abstract

Fe2O3-x spinel-structure thin films grown by pulsed laser deposition (PLD) and commercially available magnetite nanoparticles were subjected to electrochemical lithiation at room temperature. A substantial decrease in saturation magnetization (Ms) was observed both in the PLD-grown thin films and nanoparticles on lithiation. Further, lithiation of PLD-grown thin films and nanoparticles has resulted in a reduction in intensity of the 311, 220 and 440 reflections in XRD. A decrease in Ms of up to 30% for thin films and 75% for nanoparticles has been observed by discharging down to 0.9 V versus Li/Li+. The decrease in saturation magnetization upon lithiation may be due to formation of a paramagnetic phase. The smaller drop in Ms observed in thin films could be a kinetic effect due to the high density of the PLD-grown films and hence lithiation of only the surface layers.