Cation Ordering in LiFe5O8 Studied by Mössbauer Spectroscopy and X-Ray Crystallography

Abstract

In order to establish the atomic order (or disorder) of Li atoms in LiFe5O8, a crystallographic structure refinement and a spectroscopic Mössbauer study are made. Several polycrystalline and monocrystalline samples are separately heat treated and studied. The results are in agreement with the existence of a short‐range order in the disordered phase. An exact fit of the Mössbauer spectra is done and distinguishes three FeB sites and two FeA sites magnetically inequivalent. The calulated dipolar fields are consistent with values determined by NMR.

Cation Distribution in Ordered Spinels of the Li2O–TiO2–Fe2O3System

“…According to the literature, the expected value of the isomer shift of octahedral Fe> is more positive than that of the tetrahedral Fe> (19,25). Consequently, and as lithium occupies (4b) sites, the more intense subspectrum in Fig.…”

The Influence of Mechanical Milling and Subsequent Calcination on the Formation of Lithium Ferrites

“…A -phase has the same structure but with the Li> and Fe> ions randomly distributed in the octahedral interstices. The transition from the ordered -phase to the disorderedphase occurs at ca 7553C (5,6). The preparation of polycrystalline lithium ferrites has been achieved by a variety of methods including #ash "ring (1), sintering of carbonates and oxides (6,7), and spray drying of lithium and iron formates followed by sintering (8).…”

Affinement de la structure des formes ordonnée et désordonnée de l'octaoxopentaferrate de lithium, LiFe5O8

“…Une transition de type ordre-d~sordre existe entre ces deux formes dans l'intervalle de temperature 1008 -1028 K. Le passage de la forme d6sordonn6e ~. la forme ordonn+e se traduit sur les clich+s de diffraction par la presence de r~flexions suppl6mentaires de profil +largi (Cheary & Grimes, 1978 (Dormann, Nogues & Tomas, 1983), de d6terminer sur un monocristal, par diffraction des rayons X, la structure des formes ordonn6e et d+sordonn6e de LiF%O 8. (Fe,Li) (1) …”