Physical and electrochemical properties of iron-doped lithium–manganese-spinels prepared by different methods

Mateyshina, Yu. G.; Lafont, Ugo; Уваров, Н. Ф.; Kelder, E.M.

doi:10.1016/j.ssi.2007.12.067

Cited by 12 publications

(20 citation statements)

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“…Both patterns can be assigned to LiFeMnO 4 , , but the diffractogram corresponding to the Cer sample showed additional peaks at 37.06° and 44.75° 2θ positions ( d -spacing = 24.26 and 20.25 nm, respectively). The presence of similar XRD peaks in some samples with compositions close to LiFeMnO 4 , prepared from different methods, had been also observed. ,, These peaks were assigned to impurities, ,, mainly constituted by a mixture of spinel phases (likely to be an iron-enriched phase) and to Li 2 MnO 3 . We think that these small extra peaks would be due to the presence of the lithium iron manganese oxide Li 2 Fe 0.5 Mn 1.5 O 4 as a minor constituent .…”

Section: Resultsmentioning

confidence: 52%

“…The first compound of the series, LiFeMnO 4 ( x = 0), which was not included in our previous studies, appears interesting because the three metals are simultaneously present with identical stoichiometry. From the literature data it can deduced ,,− , that, in the spinel-related structure of LiFeMnO 4 , the Li + and Fe 3+ ions share the tetrahedral A sites, whereas the 16d octahedral B sites are occupied by Li + , Fe 3+ , and Mn 4+ ions. The atomic metal occupancy reported for this oxide is (Li 0.6 Fe 0.4 )[Li 0.4 Fe 0.6 Mn]O 4 . ,,,, However, data obtained from distinct synthetic samples showed discrepancies in the cation distribution over the spinel sublattices, the oxidation state of Mn, and the stoichiometry of the oxide.…”

Section: Introductionmentioning

confidence: 99%

“…Quenched samples usually show both a larger lattice parameter and different electrochemical properties . Also, as it is usual in the preparation of the Li−Fe−Mn−O series, the synthesis conditions are not well-optimized; it is necessary to try different strategies of preparation because all structural parameters are highly dependent on the reaction conditions and the various processing steps. ,,,, In general, synthesis procedures are based on a solid−solid state reaction induced by thermal treatments upon solid starting materials, such as mixtures of carbonates, oxalates, oxides, or hydroxides, in the adequate metal molar ratio for the desired oxide composition. Sol−gel, hydrothermal processes, ball-milling, or thermal decomposition of the proper metal nitrates are other common synthetic routes .…”

Section: Introductionmentioning

confidence: 99%

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Characterization of The Lithium−Manganese Ferrite LiFeMnO₄ Prepared by Two Different Methods

et al. 2010

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Lithium−manganese ferrite LiFeMnO4 was prepared using two different methods: a conventional ceramic high-temperature solid-state reaction technique (Cer) and thermal decomposition of metal nitrate salts (NTD). The characterization of the compounds was carried out by SEM/EDX, XRD, XPS, Fe K- and Mn K-edge XANES, and Mössbauer spectroscopy. Both Cer and NTD LiFeMnO4 samples have the nominal expected Fe/Mn atomic ratio and show a homogeneous morphology, but they exhibit different particle sizes. Fe K-edge XANES and Mössbauer spectroscopy results show that the oxidation state of Fe ions is +3 in both samples, whereas the Mn K-edge XANES data indicate that the bulk average Mn oxidation state is +3 for the NTD sample and close to +4 for the Cer one. Thus, to maintain the charge neutrality, the NTD sample has to be nonstoichiometric in oxygen with a composition close to LiFeMnO3.5. The Mn 3s XPS data indicate that the average surface oxidation state of Mn is also lower in the NTD sample. The results suggest the occurrence of small Fe clusters inside the spinel-related structure in both samples. The Fe cluster occurrence can be due to the presence of diamagnetic Li+ ions, which share both tetrahedral and octahedral sites with the Fe3+ ions. This can result in different configurations around the Fe-occupied sites such that some of the Fe3+ ions located at the octahedral sites remain in a paramagnetic state at 298 K and, therefore, are responsible for the doublet observed in the corresponding Mössbauer spectrum. The neighboring Mn-rich regions containing Mn3+ or Mn4+ ions in octahedral positions also modify the existing magnetic interactions in such a way that they become more complex in the NTD sample than in the Cer one, which is reflected in a more marked superparamagnetic-like behavior. This suggests the existence in the NTD sample of a larger amount of Fe clusters, which can be explained by the different oxidation states of Mn, a larger number of oxygen vacancies, and a higher number of Fe sites with reduced coordination in this material. Finally, the differences found in the chemical and structural properties of Cer and NTD samples can be due not only to variations in thermal treatments used in each synthesis procedure but also to the different nature of the starting products in both methods.

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Section: Resultsmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of The Lithium−Manganese Ferrite LiFeMnO₄ Prepared by Two Different Methods

et al. 2010

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“…The doping elements are metals: either non-transition, e.g. Al, Mg [14][15][16][17][18][19], or transition metals Ni [20][21][22][23][24][25][26][27][28][29][30][31], Fe [14,[32][33][34][35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Formation of Fe and Ni substituted LiMn_2–XM_XO₄nanopowders and their crystal and electronic structure and magnetic properties

Talik

Lipińska

Guzik

et al. 2017

Materials Science-Poland

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The Pechini sol-gel method was applied to obtain LiMn 2 − x T x O 4 (T = Ni, Fe; x = 0.1 to 0.5) nanopowders. Crystal and electronic structures, chemical composition and magnetic properties of the materials were characterized by X-ray diffraction, XPS, SEM/EDX microscopy, prompt gamma-ray activation analysis (PGAA), Mössbauer spectroscopy and magnetic susceptibility, respectively. XRD measurements showed that the LiMn 2 − x Ni x O 4 were single phase for x = 0.1 and 0.2. Three samples with higher Ni content contained some addition of a second phase. Analysis of the oxidation state of the dopants by XPS revealed ionic Ni 2+ and Fe 3+ . Mössbauer spectroscopy also confirmed 3+ oxidation state of iron and its location in octahedral sites, which excluded the inverse spinel configuration. XPS examinations showed that Mn 3+ ions dominated in the iron substituted series whereas the Mn 4+ was dominant in the nickel series.

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“…26 The excess of Li + ions in the spinel structure also promotes its doping. 27,28 Additionally, anionic doping replaces small amounts of O 2-ions in the spinel framework and therefore minimizes the disproportionation reaction of Mn 3+ ions and the instability of the spinel structure due to oxygen loss (as mentioned above ions by other trivalent cations leads to increased ν values, as reported, e.g., by Amaral et al 3 Therefore, the average manganese valence of doped spinels is a useful parameter because it can provide information on their effective doping and structural changes.…”

Section: Introductionmentioning

confidence: 99%

A New, Friendlier Methodology to Determine the Average Manganese Valence in LixMn2O4 Spinels Using Atomic Absorption Spectrometry and Molecular Absorption Spectrophotometry

Silva¹,

Silva²,

Biaggio³

et al. 2017

J. Braz. Chem. Soc.

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An alternative, friendlier methodology for the determination of the average manganese valence (ν) of manganese oxides (mainly pure and doped spinels) is presented. This methodology is based on the facile determination of the concentration of Mn 2+ and Fe 2+ ions by atomic absorption spectrometry (AAS) and molecular absorption spectrophotometry (MAS), respectively. Prior to this determination, the manganese oxides are reacted with an acidic solution containing Fe 2+ ions, when all Mn ν+ ions are reduced to Mn 2+. Then, the concentration of Mn 2+ ions is obtained directly by AAS, whereas that of Fe 2+ ions is obtained by MAS after their complexation with o-phenanthroline. Using this methodology, the obtained mean (n = 3) ν values for the stoichiometric oxides Mn 2 O 3 and Mn 3 O 4 are 2.98 ± 0.01 and 2.66 ± 0.01, respectively; their precision is a clear evidence of the suitability of the here-proposed methodology. Additionally, a precise mean ν value (3.46 ± 0.01; n = 3) is also obtained for the spinel Li 1.05 Mn 2 O 4 , whereas a higher ν value (3.52 and 3.53; n = 2) is obtained for the doped spinel Li 1.05 Mn 1.98 Al 0.02 O 3.98 S 0.02 , evidencing that effective doping has been indeed attained. This novel methodology is easily applicable for Mn oxides in electrode materials of many energy storage devices. Keywords IntroductionIn the last decade, the popularization of portable electronic devices has increased, leading to a growing demand for lithium ion batteries (LIBs). In this scenario, some oxides have been targeted for studying and testing as cathode materials in LIBs; the spinel lithium manganese oxide (Li x Mn 2 O 4 ) is one of these oxides.1,2 The use of this spinel is favored by factors such as the manganese abundance, non-toxicity, and low cost, as well as the possibility of insertion of two lithium ions per formula unit.3 When 0 ≤ x ≤ 1, Li 3 Therefore, the average manganese valence of doped spinels is a useful parameter because it can provide information on their effective doping and structural changes.As far as we could ascertain, the most common approach to determine the average manganese valence of manganese oxides has been the Vetter and Jaeger's method, 33 employs an acid solution of potassium iodide to reduce all Mn ions in the manganese oxides to Mn 2+ ions. In this process, iodine is formed and quantified by titration with a sodium thiosulfate solution, while Mn 2+ ions are determined by titration with an EDTA solution. Titration of iodine was also proposed by Licci et al. 34 to determine the average manganese valence in Mn-La complexes. Firstly, after the Mn-La complex is dissolved in dilute H 2 SO 4 , the Mn ions are oxidized to permanganate ions by adding an excess of solid bismuthate, followed by the addition of an iodide solution (also in excess) that converts all permanganate ions into Mn 2+ ions, yielding iodine. In a parallel step, the Mn-La complex is reacted directly with an iodide solution, also yielding iodine. In both cases, the iodine is amperometrically titrated with a thio...

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Physical and electrochemical properties of iron-doped lithium–manganese-spinels prepared by different methods

Cited by 12 publications

References 12 publications

Characterization of The Lithium−Manganese Ferrite LiFeMnO₄ Prepared by Two Different Methods

Characterization of The Lithium−Manganese Ferrite LiFeMnO₄ Prepared by Two Different Methods

Formation of Fe and Ni substituted LiMn_2–XM_XO₄nanopowders and their crystal and electronic structure and magnetic properties

A New, Friendlier Methodology to Determine the Average Manganese Valence in LixMn2O4 Spinels Using Atomic Absorption Spectrometry and Molecular Absorption Spectrophotometry

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Physical and electrochemical properties of iron-doped lithium–manganese-spinels prepared by different methods

Cited by 12 publications

References 12 publications

Characterization of The Lithium−Manganese Ferrite LiFeMnO4 Prepared by Two Different Methods

Characterization of The Lithium−Manganese Ferrite LiFeMnO4 Prepared by Two Different Methods

Formation of Fe and Ni substituted LiMn2–XMXO4nanopowders and their crystal and electronic structure and magnetic properties

A New, Friendlier Methodology to Determine the Average Manganese Valence in LixMn2O4 Spinels Using Atomic Absorption Spectrometry and Molecular Absorption Spectrophotometry

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Characterization of The Lithium−Manganese Ferrite LiFeMnO₄ Prepared by Two Different Methods

Characterization of The Lithium−Manganese Ferrite LiFeMnO₄ Prepared by Two Different Methods

Formation of Fe and Ni substituted LiMn_2–XM_XO₄nanopowders and their crystal and electronic structure and magnetic properties