Neutron diffraction studies of the magnetic ordering in the spinel oxide system Mg Co1−Cr Fe2−O4

Yunus, S.M.; Yamauchi, Hiroki; Zakaria, A.K.M.; Igawa, Naoki; Hoshikawa, Akinori; Haga, Yoshinori; Ishii, Yoshinobu

doi:10.1016/j.jallcom.2007.05.097

Cited by 14 publications

(5 citation statements)

References 21 publications

(46 reference statements)

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“…LeBail fit of powder diffraction patterns (Supporting Information, Figures S40− S42) confirms the expected increase of the unit-cell size on going from the Co-rich residue obtained by thermolysis of precursor 2 to more Fe-rich samples derived from 1 and 3 (Supporting Information, Table S45). The former oxide residue corresponds well to the reported 11c FeCo 2 O 4 spinel, while the latter residues fell closer to that of Fe 2 CoO 4 33 and are best described in the cubic space group Fd3̅ m.…”

Section: ■ Introductionsupporting

confidence: 73%

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

et al. 2017

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A series of mixed-valent, heterometallic (mixed-transition metal) diketonates that can be utilized as prospective volatile single-source precursors for the low-temperature preparation of MM'O spinel oxide materials is reported. Three iron-cobalt complexes with Fe/Co ratios of 1:1, 1:2, and 2:1 were synthesized by several methods using both solid-state and solution reactions. On the basis of nearly quantitative reaction yields, elemental analyses, and comparison of metal-oxygen bonds with those in homometallic analogues, heterometallic compounds were formulated as [Fe(acac)][Co(hfac)] (1), [Co(hfac)][Fe(acac)][Co(hfac)] (2), and [Fe(hfac)][Fe(acac)][Co(hfac)] (3). In the above heteroleptic complexes, the Lewis acidic, coordinatively unsaturated Co/Fe centers chelated by two hexafluoroacetylacetonate (hfac) ligands maintain bridging interactions with oxygen atoms of acetylacetonate (acac) groups that chelate the neighboring Fe metal ion. Preliminary assignment of Fe and Co positions/oxidation states in 1-3 drawn from X-ray structural investigation was corroborated by a number of complementary techniques. Single-crystal resonant synchrotron diffraction and neutron diffraction experiments unambiguously confirmed the location of Fe and Co sites in the molecules of dinuclear (1) and trinuclear (2) complexes, respectively. Direct analysis in real time mass spectrometry revealed the presence of Fe- and Co-based fragments in the gas phase upon evaporation of precursors 1 and 2 as well as of Fe, Fe, and Co species for complex 3. Theoretical investigation of two possible "valent isomers", [Fe(acac)][Co(hfac)] (1) and [Co(acac)][Fe(hfac)] (1'), provided an additional support for the metal site/oxidation state assignment giving a preference of 6.48 kcal/mol for the experimentally observed molecule 1. Magnetic susceptibility measurements data are in agreement with the presence of high-spin Fe and Co magnetic centers with weak anti-ferromagnetic coupling between those in molecules of 1 and 2. Highly volatile heterometallic complexes 1-3 were found to act as effective single-source precursors for the low-temperature preparation of iron-cobalt spinel oxides FeCoO known as important materials for diverse energy-related applications.

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Section: ■ Introductionsupporting

confidence: 73%

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

et al. 2017

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“…The general formula for the cationic distribution is (A 1Àg B g ) T [B 2Àg A g ] O O 4 ; where g is the degree of inversion (0 g 1.0) and T and O indicate tetrahedral and octahedral sites, respectively. A knowledge of the cation distribution between O and T sites is crucial, since it determines the magnetic and electrical properties of the spinels, thus, the knowledge of this distribution is important in controlling and predicting the physical properties of spinels [2,3]. Neutrons diffraction (ND) can give an unambiguous picture of this distribution, since usually neutron coherent scattering lengths significantly differ for the different cations, consequently ND is essential in studying cations distribution in spinels.…”

Section: Introductionmentioning

confidence: 99%

Crystal and magnetic structure and cation distribution of Mn2−xV1+xO4 spinels (x=0, 1/3 and 1)

Pannunzio-Miner

Paoli

Sánchez

et al. 2009

Materials Research Bulletin

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“…The second transition, at Curie temperature, is due to the magnetic-phase transition from ferrimagnetic to paramagnetic states [25]. Figure (7) also shows the relation between the Curie temperature Tc and the concentration of Co 3+ content .From inspection of this figure it is reveals that the Curie temperature Tc is shifted to higher temperatures with increasing Co 3+ ions substitution [29]. This behavior may be due to the replacement of Fe ions by the Co ions in octahedral sites [1].…”

Section: Temperature Dependence Of the Initial Magnetic Permeabilitymentioning

confidence: 91%

Thermoelectric Power and Magnetic Permeability of Cd0.4Mn0.6CoxFe2-xO4 ferrite system

2010

Egyptian Journal of Solids

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Neutron diffraction studies of the magnetic ordering in the spinel oxide system Mg Co1−Cr Fe2−O4

Cited by 14 publications

References 21 publications

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

Crystal and magnetic structure and cation distribution of Mn2−xV1+xO4 spinels (x=0, 1/3 and 1)

Thermoelectric Power and Magnetic Permeability of Cd0.4Mn0.6CoxFe2-xO4 ferrite system

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