Neutron diffraction study of the inverse spinels 
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Thota, Subhash; Reehuis, M.; Maljuk, A.; Hoser, A.; Hoffmann, J.-U.; Weise, Bruno; Waske, Anja; Krautz, Maria; Joshi, D. C.; Nayak, Sisir Kumar; Ghosh, Sheuly; Suresh, P.; Dasari, Kiran; Wurmehl, S.; Prokhnenko, O.; Büchner, B.

doi:10.1103/physrevb.96.144104

Cited by 36 publications

(41 citation statements)

References 82 publications

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“…Figure 4(a) presents the Co2p spectra of T 1 and T 2 , respectively, indicating that there are doublet peaks of Co 2p 3/2 and Co 2p 1/2 located at 780.46 and 795.96 eV for T 1 and 780.62 and 796 eV for T 2 , respectively. The energy splitting (ΔE) values of the divalent and trivalent Co ions are 15.4 and 15.1 eV for T 1 and T 2 , respectively, which are consistent with values reported in the literature 19 . The Co2p spectra of T 1 and T 2 are fitted into six peaks with binding energies of approximately 780.4 and 795.8 eV for Co 2+ and 782.2 and 797.3 eV for Co 3 + 5,19 .…”

Section: Resultssupporting

confidence: 90%

“…The energy splitting (ΔE) values of the divalent and trivalent Co ions are 15.4 and 15.1 eV for T 1 and T 2 , respectively, which are consistent with values reported in the literature 19 . The Co2p spectra of T 1 and T 2 are fitted into six peaks with binding energies of approximately 780.4 and 795.8 eV for Co 2+ and 782.2 and 797.3 eV for Co 3 + 5,19 . Furthermore, two satellite peaks are observed at 786.13 and 802.6 eV for T 1 and 785.84 and 802.45 eV for T 2 , respectively 19 .…”

Section: Resultssupporting

confidence: 90%

“…The Co2p spectra of T 1 and T 2 are fitted into six peaks with binding energies of approximately 780.4 and 795.8 eV for Co 2+ and 782.2 and 797.3 eV for Co 3 + 5,19 . Furthermore, two satellite peaks are observed at 786.13 and 802.6 eV for T 1 and 785.84 and 802.45 eV for T 2 , respectively 19 . The concentrations of Co 2+ and Co 3+ are 63% and 37% for T 1 and 70% and 30% for T 2 , respectively(as listed in Table 1).…”

Section: Resultsmentioning

confidence: 99%

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Role of precursors mixing sequence on the properties of CoMn2O4 cathode materials and their application in pseudocapacitor

Pattanayak

Simanjuntak

Panda

et al. 2019

Sci Rep

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In this study, the effect of oxygen vacancy in the CoMn2O4 on pseudocapacitive characteristics was examined, and two tetragonal CoMn2O4 spinel compounds with different oxygen vacancy concentrations and morphologies were synthesized by controlling the mixing sequence of the Co and Mn precursors. The mixing sequence was changed; thus, morphologies were changed from spherical nanoparticles to nanoflakes and oxygen vacancies were increased. Electrochemical studies have revealed that tetragonal CoMn2O4 spinels with a higher number of oxygen vacancies exhibit a higher specific capacitance of 1709 F g−1 than those with a lower number of oxygen vacancies, which have a higher specific capacitance of 990 F g−1. Oxygen vacancies create an active site for oxygen ion intercalation. Therefore, oxidation–reduction reactions occur because of the diffusion of oxygen ions at octahedral/tetrahedral crystal edges. The solid-state asymmetric pseudocapacitor exhibits a maximum energy density of 32 Wh-kg−1 and an excellent cyclic stability of nearly 100%.

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Role of precursors mixing sequence on the properties of CoMn2O4 cathode materials and their application in pseudocapacitor

Pattanayak

Simanjuntak

Panda

et al. 2019

Sci Rep

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“…From the occupations observed, it was concluded that the cationic distribution for the CTO in CTO/RGO is (Co 0.98 Ti 0.02 ) Td (Co 0.96 Ti 1.04 ) Oh O 4 and in CTO+RGO is (Co 0.96 Ti 0.04 ) Td (Co 0.98 Ti 1.02 ) Oh O 4. These results indicate that the tetrahedral sites are not fully occupied by Co 2+ ions since there is a small amount of Ti 4+ , unlike the work reported by S. Thota et al, where CTO was synthesized by a solid-state reaction, with Co 2+ and Co 3+ in both crystallographic sites and Ti 3+ in the octahedral site [48,60]. These differences in the distribution of the cations in the crystallographic sites can be attributed to the method of synthesis and the precursors used, suggesting that the lower reaction temperature possibly means there is insufficient energy to permit full ordering or mixing of the cations, and thus some inhomogeneity persists.…”

Section: Resultsmentioning

confidence: 74%

Co2TiO4/Reduced Graphene Oxide Nanohybrids for Electrochemical Sensing Applications

et al. 2019

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For the first time, the synthesis, characterization, and analytical application for hydrogen peroxide quantification of the hybrid materials of Co2TiO4 (CTO) and reduced graphene oxide (RGO) is reported, using in situ (CTO/RGO) and ex situ (CTO+RGO) preparations. This synthesis for obtaining nanostructured CTO is based on a one-step hydrothermal synthesis, with new precursors and low temperatures. The morphology, structure, and composition of the synthesized materials were examined using scanning electron microscopy, X-ray diffraction (XRD), neutron powder diffraction (NPD), and X-ray photoelectron spectroscopy (XPS). Rietveld refinements using neutron diffraction data were conducted to determine the cation distributions in CTO. Hybrid materials were also characterized by Brunauer–Emmett–Teller adsorption isotherms, Scanning Electron microscopy, and scanning electrochemical microscopy. From an analytical point of view, we evaluated the electrochemical reduction of hydrogen peroxide on glassy carbon electrodes modified with hybrid materials. The analytical detection of hydrogen peroxide using CTO/RGO showed 11 and 5 times greater sensitivity in the detection of hydrogen peroxide compared with that of pristine CTO and RGO, respectively, and a two-fold increase compared with that of the RGO+CTO modified electrode. These results demonstrate that there is a synergistic effect between CTO and RGO that is more significant when the hybrid is synthetized through in situ methodology.

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“…Additionally, magnetic interaction mechanisms in Co 2 VO 4 have been proposed using semi-empirical rules for magnetic interactions in spinels [18,20]. While temperature-driven magnetization reversal for Co 2 VO 4 , Co 2 TiO 4 , and Sr 2 DyRuO 6 has been experimentally explored [18,[21][22][23][24], the fundamental driving mechanism behind MR in the inverse spinels remains to be understood.…”

Section: Introductionmentioning

confidence: 99%

Localized-delocalized crossover of spin-carriers and magnetization reversal in Co$_{2}$VO$_{4}$

Kademane¹,

Bhandari²,

Paudyal³

et al. 2021

Preprint

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Neutron diffraction, magnetization and muon spin relaxation measurements, supplemented by density functional theory (DFT) calculations are employed to unravel temperature-driven magnetization reversal (MR) in inverse spinel Co2VO4. All measurements show a second order magnetic phase transition at TC = 168 K to a collinear ferrimagnetic phase. The DFT results suggest the moments in the ferrimagnetic phase are delocalized and undergo gradual localization as the temperature is lowered below TC. The delocalized-localized crossover gives rise to a maximum magnetization at TNC = 138 K and the continuous decrease in magnetization produces sign-change at TMR ∼ 65 K. Muon spectroscopy results support the DFT, as a strong T1-relaxation is observed around TNC, indicating highly delocalized spin-carriers gradually tend to localization upon cooling. The magnetization reversal determined at zero field is found to be highly sensitive to applied magnetic field, such that above B ∼ 0.25 T instead of a reversal a broad minimum in the magnetization is apparent at TMR. Analysis of the neutron diffraction measurements shows two antiparallel magnetic sublattice-structure, each belonging to magnetic ions on two distinct crystal lattice sites. The relative balance of these two structural components in essence determines the magnetization. Indeed, the order parameter of the magnetic phase on one site develops moderately more than that on the other site. Unusual tipping of the magnetic balance, caused by such site-specific magnetic fluctuation, gives rise to a spontaneous flipping of the magnetization as the temperature is lowered. * A.B.K and C.B contributed equally.[1] M. Néel, Propriétés magnétiques des ferrites ; ferrimagnétisme et antiferromagnétisme, Annales De Physique 12, 137 (1948). [2] Y. Yafet and C. Kittel, Antiferromagnetic arrangements in ferrites, Physical Review 87, 290 (1952).

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Neutron diffraction study of the inverse spinels Co2TiO4 and Co2SnO4

Cited by 36 publications

References 82 publications

Role of precursors mixing sequence on the properties of CoMn2O4 cathode materials and their application in pseudocapacitor

Role of precursors mixing sequence on the properties of CoMn2O4 cathode materials and their application in pseudocapacitor

Co2TiO4/Reduced Graphene Oxide Nanohybrids for Electrochemical Sensing Applications

Localized-delocalized crossover of spin-carriers and magnetization reversal in Co$_{2}$VO$_{4}$

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