Manganites de fer de structure spinelle déformée à très fort champ coercitif. Exemple de l'oxyde lacunaire à valence mixte Mn1,7Fe1,3O4+δ

Agnoli, F.; Albouy, Boris; Tailhades, Philippe; Rousset, A.

doi:10.1016/s1387-1609(00)86438-5

Cited by 2 publications

(5 citation statements)

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“…13a, the calculated cationic distribution evidences that the amount of Mn 2+ on octahedral sites of the spinel strongly increases in the cubic spinel. Furthermore, it has been shown that Mn 2+ on octahedral sites is easier to oxidize than Mn 2+ on tetragonal sites [24]. This difference might very well explain the reason why the cycling properties of the cubic spinel are much better than those of the tetragonal spinel.…”

Section: Manganese-based Mixed Oxidesmentioning

confidence: 99%

High-temperature thermochemical energy storage based on redox reactions using Co-Fe and Mn-Fe mixed metal oxides

André

Abanades

Cassayre

2017

Journal of Solid State Chemistry

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Metal oxides are potential materials for thermochemical heat storage via reversible endothermal/exothermal redox reactions, and among them, cobalt oxide and manganese oxide are attracting attention. The synthesis of mixed oxides is considered as a way to answer the drawbacks of pure metal oxides, such as slow reaction kinetics, loss-incapacity over cycles or sintering issues, and the materials potential for thermochemical heat storage application needs to be assessed. This work proposes a study combining thermodynamic calculations and experimental measurements by simultaneous thermogravimetric analysis and calorimetry, in order to identify the impact of iron oxide addition to Co and Mn-based oxides. Fe addition decreased the redox activity and energy storage capacity of Co 3 O 4 /CoO, whereas the reaction rate, reversibility and cycling stability of Mn 2 O 3 /Mn 3 O 4 was significantly enhanced with added Fe amounts above~15 mol%, and the energy storage capacity was slightly improved. The formation of a reactive cubic spinel explained the improved re-oxidation yield of Mn-based oxides that could be cycled between bixbyite and cubic spinel phases, whereas a low reactive tetragonal spinel phase showing poor re-oxidation was formed below 15 mol% Fe. Thermodynamic equilibrium calculations predict accurately the behavior of both systems. The possibility to identify other suitable mixed oxides becomes conceivable, by enabling the selection of transition metal additives for tuning the redox properties of mixed metal oxides destined for thermochemical energy storage applications.

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Section: Manganese-based Mixed Oxidesmentioning

confidence: 99%

High-temperature thermochemical energy storage based on redox reactions using Co-Fe and Mn-Fe mixed metal oxides

André

Abanades

Cassayre

2017

Journal of Solid State Chemistry

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“…This analysis has been performed on the stoechiometric spinel of composition x = 1.3 and gives the following cationic distribution [3] This cationic distribution is closed to the cationic distribution of an oxide of same composition, made at high temperature (T=1 100 'C) and analyzed by Mossbauer technique [14,15]. The coercive field of the stoechiometric spinel prepared for our work, was 100 Oe (-0.8 kA.m-l).…”

Section: Cationic Distribution and Magnetic Propertiesmentioning

confidence: 91%

“…The structural formula was estimated to be: At this temperature, only the Mn2+ ions in octahedral sites have been oxidized into Mn3+ ions. The coercive field was measured at 2500 Oe (-200 kA.ml), is closed to the coercive field determined by A. Agnoli [3].…”

Section: Cationic Distribution and Magnetic Propertiesmentioning

confidence: 99%

“…Recently, the interest of these materials has greatly increased with the discovery of hard magnetic properties in metastable manganese 3+ ferrites. These properties are due to the distortion of the Mn cations in the spinel structure by the Jahn-Teller effect [3]. The same bulk ferrites (without Cobalt) are well known to be soft magnetic materials.…”

Section: Introductionmentioning

confidence: 99%

“…The phase diagram of the Fe/Mn/O system [5] shows that the spinel phase can be obtained in air at temperature above 950'C. Only a few works have been published on the synthesis of this stoechiometric spinel at low temperature [3,6,7]. Probably, the difficulty to obtain the stoechiometric spinel at low temperature is due to, the need of a better control of the reduction atmosphere, the weak crystallinity of the samples and the immiscibility gap described by Masson [8] for the natural "wredenburgite".…”

Section: Introductionmentioning

confidence: 99%

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Iron Manganites Synthesis by the Soft Chemistry Method

et al. 2001

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The iron manganites FexMn( 3 _X)0 4 synthesis by soft chemistry method have been studied. The main difficulty is to obtain single phase spinel with high Mn content (0.4< x < 1.3). Oxalate precursor powders of these materials with controlled shape and nanoscopic size have been prepared. The precursors are then heat treated with a H2/H 2 O/N 2 gas mixture at low temperature. The resulting stoechiometric spinels are metastable phases with high specific surface area and are highly reactive toward oxygen. Therefore, these oxide can be oxidized in air at low temperature in order to produce mixed valence defect manganites 0 4+8 with a good reproducibility on the oxygen content. Although, some problems persist for the higher Mn contents, as the oxygen partial pressure for the reduction must be controlled precisely in order to produce the stoechiometric spinel at low temperature. The development of a low temperature reduction system, with oxygen partial pressure controlled by oxygen electrochemical pumping, is in progress.

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Manganites de fer de structure spinelle déformée à très fort champ coercitif. Exemple de l'oxyde lacunaire à valence mixte Mn1,7Fe1,3O4+δ

Cited by 2 publications

References 5 publications

High-temperature thermochemical energy storage based on redox reactions using Co-Fe and Mn-Fe mixed metal oxides

High-temperature thermochemical energy storage based on redox reactions using Co-Fe and Mn-Fe mixed metal oxides

Iron Manganites Synthesis by the Soft Chemistry Method

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