Structure and cation ordering in spinel-type TcCo2O4. An example of a trivalent technetium oxide

Thorogood, Gordon J.; Zhang, Zhaoming; Hester, James; Kennedy, Brendan J.; Ting, Jason C.; Glover, Christopher; Johannessen, Bernt

doi:10.1039/c1dt10954e

Cited by 8 publications

(7 citation statements)

References 23 publications

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“…In spinel structures,c obalt can occur in multiple oxidation states (+ II and + III), in which the high-spin Co2 + occupy the tetrahedral Ao ro ctahedral Bs ites whereas the low-spinC o3 + occupies only the octahedral sites. [28] To furtherc onfirmt he cation distribution,X -ray photoelectron spectroscopy (XPS) analysiso ft he RCO100 sample was performed (see Figure 1b-d). The full-scan survey spectrumo ft he material( see S2) indicated the presence of C1s, O1s, Co 2p, Ru 3p, and Ru 3d as well as the absence of other impurities.…”

Section: Mðohþ 2ðsþmentioning

confidence: 99%

Ultrathin Mesoporous RuCo₂O₄Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

et al. 2017

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A new ruthenium cobalt oxide (RuCo O ) with a unique marigold-like nanostructure and excellent performance as an advanced electrode material has been successfully prepared by a simple electrodeposition (potentiodynamic mode) method. The RuCo O marigolds consist of numerous clusters of ultrathin mesoporous nanoflakes, leaving a large interspace between them to provide numerous electrochemically active sites. Strikingly, this unique marigold-like nanostructure provided excellent electrochemical performance in terms of high energy-storage capacitance (1469 F g at 6 A g ) with excellent rate proficiency and long-lasting operating cycling stability (ca. 91.3 % capacitance retention after 3000 cycles), confirming that the mesoporous nanoflakes participate in the ultrafast electrochemical reactions. Furthermore, an asymmetric supercapacitor was assembled using RuCo O (positive electrode) and activated carbon (negative electrode) with aqueous KOH electrolyte. The asymmetric design allowed an upgraded potential range of 1.4 V, which further provided a good energy density of 32.6 Wh kg (1.1 mWh cm ). More importantly, the cell delivered an energy density of 12.4 Wh kg even at a maximum power density of 3.2 kW kg , which is noticeably superior to carbon-based symmetric systems.

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Section: Mðohþ 2ðsþmentioning

confidence: 99%

Ultrathin Mesoporous RuCo₂O₄Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

et al. 2017

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“…Because of the radioactive nature of technetium, there are relatively few tools available for analyzing the electronic properties of these materials compared with the other 4d transition metals. Tc K-edge X-ray absorption near-edge structure (XANES) has proven to be an effect tool for studying the oxidation state and coordination environment of Tc (Antonini et al, 1983;Almahamid et al, 1995;Mausolf et al, 2011;Poineau et al, 2008;Ferrier et al, 2012;Thorogood et al, 2011b). However, the Tc K-edge XANES spectrum, which predominantly corresponds to the dipole transition of 1s electrons into empty 5p states, is limited by a broad line shape and can only provide indirect information on the Tc 4d bonding states via the unoccupied p component in p-d hybridized orbitals.…”

Section: Introductionmentioning

confidence: 99%

An unconventional method for measuring the TcL₃-edge of technetium compounds

Blanchard

Reynolds

Kennedy

et al. 2014

J Synchrotron Radiat

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Tc L3-edge XANES spectra have been collected on powder samples of SrTcO3 (octahedral Tc(4+)) and NH4TcO4 (tetrahedral Tc(7+)) immobilized in an epoxy resin. Features in the Tc L3-edge XANES spectra are compared with the pre-edge feature of the Tc K-edge as well as other 4d transition metal L3-edges. Evidence of crystal field splitting is obvious in the Tc L3-edge, which is sensitive to the coordination number and oxidation state of the Tc cation. The Tc L3 absorption edge energy difference between SrTcO3 (Tc(4+)) and NH4TcO4 (Tc(7+)) shows that the energy shift at the Tc L3-edge is an effective tool for studying changes in the oxidation states of technetium compounds. The Tc L3-edge spectra are compared with those obtained from Mo and Ru oxide standards with various oxidation states and coordination environments. Most importantly, fitting the Tc L3-edge to component peaks can provide direct evidence of crystal field splitting that cannot be obtained from the Tc K-edge.

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“…Most research into Tc mixed oxides (spinel, pyrochlore, perovskite, rutile, etc.) has used high-temperature sintering to produce test materials [18,21,43,44]. Many papers describe a host of alternative routes to spinel; however, only a few have been demonstrated for making Tc spinel [28,45].…”

Section: Spinelmentioning

confidence: 99%

“…Grinding the starting oxides in acetone or mixing with 20 mol% of 2NaCl:NaF used as a mineralizer increases the reactivity of oxides [50]. This method has been used with very little variation to study Tc-bearing phases [18,21,43,44].…”

Section: High-temperature Sinteringmentioning

confidence: 99%

Incorporating technetium in minerals and other solids: A review

Luksic

Riley

Schweiger

et al. 2015

Journal of Nuclear Materials

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Technetium (Tc) can be incorporated into a number of different solids including spinel, sodalite, rutile, tin dioxide, pyrochlore, perovskite, goethite, layered double hydroxides, cements, and alloys. Synthetic routes are possible for each of these phases, ranging from high-temperature ceramic sintering to ball-milling of constituent oxides. However, in practice, Tc has only been incorporated into solid materials by a limited number of the possible syntheses. A review of the diverse ways in which Tc-immobilizing materials can be made shows the wide range of options available. Special consideration is given to hypothetical application to the Hanford Tank Waste and Vitrification Plant, such as adding a Tc-bearing mineral to waste glass melter feed. A full survey of solid Tc waste forms, the common synthesis routes to those waste forms, and their potential for application to vitrification processes are presented. The use of tin dioxide or ferrite spinel precursors to reduce Tc(VII) out of solution and into a durable form are shown to be of especially high potential.

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Structure and cation ordering in spinel-type TcCo2O4. An example of a trivalent technetium oxide

Cited by 8 publications

References 23 publications

Ultrathin Mesoporous RuCo₂O₄Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

Ultrathin Mesoporous RuCo₂O₄Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

An unconventional method for measuring the TcL₃-edge of technetium compounds

Incorporating technetium in minerals and other solids: A review

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Structure and cation ordering in spinel-type TcCo2O4. An example of a trivalent technetium oxide

Cited by 8 publications

References 23 publications

Ultrathin Mesoporous RuCo2O4Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

Ultrathin Mesoporous RuCo2O4Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

An unconventional method for measuring the TcL3-edge of technetium compounds

Incorporating technetium in minerals and other solids: A review

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Product

Resources

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Ultrathin Mesoporous RuCo₂O₄Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

Ultrathin Mesoporous RuCo₂O₄Nanoflakes: An Advanced Electrode for High‐Performance Asymmetric Supercapacitors

An unconventional method for measuring the TcL₃-edge of technetium compounds