Characterization of the Mn–Li ferrite system Li1–0.5xFe1.5x+1Mn1–xO4 (0.2 ≤ x ≤ 1)

Internal iron biomineralization in Imperata cylindrica, a perennial grass: chemical composition, speciation and plant localization

“…1% of iron content). Mössbauer spectra were obtained in the temperature range of 295K to 2K, using an Oxford Spectromag 4000 m system (Oxford Instruments Inc., Oxfordshire, UK), recorded in sinusoidal mode using a conventional spectrometer with 57 Co(Rh) source (Gracia et al ., 2003). The analyses of the spectra were made by a nonlinear fit using the NORMOS program (Brand, 1987) and the energy calibration was made using a α‐Fe (6 µm) foil.…”

Order–Disorder Phase Transition and Magneto‐Dielectric Properties of (1−x)LiFe5O8–xLi2ZnTi3O8 Spinel‐Structured Solid Solution Ceramics

“…The variations in cations distribution at the A and B sites may cause marked changes in the physical properties. As an important crystal structure of ferrite, [10][11][12] the spinel-related materials have also been widely used for devices at radio frequency and microwave range as dielectrics, 13,14 and semiconductors, 15,16 etc.…”

Influence of the manganese substitution on the cation distribution and magnetic structure of the spinel-related LiFe1-xMn1 + xO4 (x = 0.00, 0.25, 0.50, 0.75) system

“…Both the cation distribution and the manganese and iron oxidation states have a great influence on the electrochemical and magnetic properties of each single phase belonging to this system. Since the thermal and chemical stability, the cation distribution, the cation oxidation states, and the electrochemical behaviour in the lithium insertion/extraction reaction are not easily deducible from theory [2], these questions have been extensively studied from various experimental points of view [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

“…In previous work we have carried out the bulk and surface characterization of the Li1-0.5xFe1.5x+1Mn1-xO4 (0.2 ≤ x ≤ 1) series by X-ray Diffraction (XRD), Mössbauer spectroscopy, X-ray Photoelectron Spectroscoopy (XPS) and Fe K-edge XANES/EXAFS [9,11] and we have also studied the electrocatalytic activity of these materials for the oxygen evolution reaction [9]. Our results [9,11] showed that: i) the Fe 3+ occupancy ratio on the tetrahedral/octahedral sublattices does not change significantly along the series, ii) the Fe 3+ ions exhibit canted spin structures on both octahedral and tetrahedral sites, iii) manganese, present as Mn 3+ and Mn 4+ ions, occupies only octahedral positions along the composition range examined, and iv) as the Li/Mn insertion progresses, the new inserted Li + ions enter on tetrahedral sites and also some of the Li + ions initially occupying octahedral sites are displaced onto tetrahedral positions. As the electrochemical properties of the Fe-doped lithium manganese oxides with composition next to that of the LiFe0.5Mn1.5O4 oxide appear to be satisfactory for lithium batteries [1,3,4], we decided to turn into the Li-Mn-Fe-O system to carry out a study of a composition series similar to that studied in [1].…”

“…The study was conducted by carrying out XRD, XPS and 57 Fe-Mössbauer spectroscopy measurements. Since obtaining pure specimens in this oxide family, especially in the case of LiFeMnO4, proved to be difficult (a first synthesis of this compound by conventional solid-state reaction techniques using Li2CO3, Fe2O3 and MnO2 as precursors and a sintering temperature of 800 o C was not successful [9,11]), we resorted then to a procedure based on a modification of a nitrate thermal decomposition (NTD) synthesis with the objective of making pure compounds.…”