Structural characterization of epitaxial LiFe5O8 thin films grown by chemical vapor deposition

Abstract

a b s t r a c tWe report on detailed microstructural and atomic ordering characterization by transmission electron microscopy in epitaxial LiFe 5 O 8 (LFO) thin films grown by chemical vapor deposition (CVD) on MgO (001) substrates. The experimental results of LFO thin films are compared with those for bulk LFO single crystal. Electron diffraction studies indicate weak long-range ordering in LFO (a-phase) thin films in comparison to bulk crystal where strong ordering is observed in optimally annealed samples. The degree of long-range ordering depends on the growth conditions and the thickness of the film. Annealing experiment along with diffraction study confirms the formation of a-Fe 2 O 3 phase in some regions of the films. This suggests that under certain growth conditions g-Fe 2 O 3 -like phase forms in some pockets in the as-grown LFO thin films that then convert to a-Fe 2 O 3 on annealing.

First‐Principles Molecular Dynamics Study of the Threshold Displacement Energy in LiFe5O8

“…Irradiation can induce antisite defects (, and ), which redistributes cations in the A‐ and B‐sites, so the order‐disorder transformation of LFO can be accomplished by electron beam irradiation. [ 16 ] An Fe Oct atom has a smaller TDE than an Fe Tetra atom, so Fe vacancies at octahedral sites (B sites) are larger than those at tetrahedral sites (A sites). Thus, irradiation leads to a decrease in magnetization, which has been observed in LFO undergoing proton irradiation.…”

“…Irradiation can lead to the creation of a wide variety of defects, such as point defects, phase changes, and clusters of defects, which modify local atomic configurations, thus affecting the magnetic properties of LFO. Various forms of irradiation, such as γ‐ray, [ 13–15 ] electron, [ 16 ] swift heavy ion, [ 17 ] proton, [ 18 ] and laser irradiation, [ 19,20 ] have been reported in the literature. Loukya et al.…”

“…Loukya et al. [ 16 ] reported that the order–disorder transition in LFO can be controlled by electron beam irradiation instead of temperature. The saturation magnetization was reduced after swift heavy ion [ 17 ] and proton irradiation.…”

A Simple, Quick and Eco-Friendly Strategy of Synthesis Nanosized α-LiFeO2 Cathode with Excellent Electrochemical Performance for Lithium-Ion Batteries

“…The cycling performance is much better than that of the reported pure phase α-LiFeO 2 [ 16 , 23 , 24 ]. The capacity decreased as the temperatures increase, which might be attributed to the higher sintering temperature leading to the impurity phase of LiFe 5 O 8 , which is considered responsible for the sharp decrease of initial discharge capacity [ 25 , 26 ]. Furthermore, Sakurai found that α-LiFeO 2 synthesized at high temperature was electrochemically inactive, as the higher temperature may increase the disorder degree of iron ions on lithium sites and block lithium diffusion pathways [ 8 , 27 , 28 ].…”