New honeycomb iridium(<scp>v</scp>) oxides: NaIrO3 and Sr3CaIr2O9

Wallace, David C.; McQueen, Tyrel M.

doi:10.1039/c5dt03188e

Cited by 40 publications

(37 citation statements)

References 37 publications

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“…The Sr 3 CaIr 2 O 9 phase, on the other hand, remains non-magnetic due to its J ef f = 0 ground state, consistent with a recent powder study. 51 The heavily substituted single crystals in the Ca 5 Ir 3 O 12 phase show an AF phase transition at T N = 9K; however at higher temperatures an anomalous anisotropy is observed in the local moment behavior. Our data provide a global view of the evolution of the ambient pressure electronic ground states and lattice stabilities of Sr-214 as increasing chemical pressure is introduced via isovalent substitution of smaller Ca cations.…”

Section: 32mentioning

confidence: 99%

“…51 No relaxation of the structure into a higher symmetry space group was observed as the system was heated to 473 K; however our PXRD measurements have poor sensitivity to the oxygen site positions and occupancies. Minimal anisotropy was observed in both transport and magnetization measurements, and our magnetization data are consistent with the picture of Sr 3 CaIr 2 O 9 possessing a non-magnetic J = 0 ground state.…”

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confidence: 99%

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Structural evolution and electronic properties of (Sr1−xCax)2−yIrO4+

Chen

Wilson

2016

Phys. Rev. B

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The effect of isoelectronic substitution within single crystals of (Sr1−xCax)2−yIrO4+z is explored. The nominal n = 1 Ruddlesden-Popper phase with y = 0, z = 0 remains stable from x = 0 until x = 0.11, where the antiferromagnet spin-orbit Mott insulating state persists. An increase in the saturated moment is observed with increasing Ca-substitution, suggesting a modified coupling of the in-plane moments relative to the in-plane rotation of IrO6 octahedra. Beyond x = 0.11, the x = 1/4, y = 0, z = 1/2 structural phase Sr3CaIr2O9, consisting of a three-dimensional network of corner sharing octahedra, begins to intermix and eventually nucleates phase pure crystals at higher starting Ca-content. An insulating, nonmagnetic ground state is observed in this phase attributable to the J = 0 state and is consistent with a recent powder study. At higher Ca-concentrations beyond x = 0.75, crystals begin to stabilize in the y = 1/3, z = 0 quasi one-dimensional Ca5Ir3O12 structure. The low temperature transport in this chain-based structure is well described via variable range hopping, and an antiferromagnetic ordering transition appears below TN = 9 K. Our data provide a detailed mapping of the electronic and structural properties accessible as the structural framework of the canonical spin orbit Mott insulator Sr2IrO4 is destabilized via isovalent chemical substitution.

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Section: 32mentioning

confidence: 99%

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confidence: 99%

Structural evolution and electronic properties of (Sr1−xCax)2−yIrO4+

Chen

Wilson

2016

Phys. Rev. B

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“…Recently the real structures of related stacking faulted iridates with honeycomb like lattices were successfully described by super positioning of different stacking types. 10,11 Based on these approaches possible stacking orders of the layers are derived from structural considerations.…”

Section: Dalton Transactions Papermentioning

confidence: 99%

“…O'Malley et al 9 observed the occurrence of stacking faults in the crystal structure of α-Li 2 IrO 3 , which is a common phenomenon in layered alkali-and earth alkali metal iridates. 10,11 Hence the slight occupational disorder between Li + and Ir 4+ in the layers, which was introduced to the structural model during the refinement, could be an artefact from daubed reflection intensities due to diffraction line broadening by the appearance of stacking faults. 10,11 The overall structural motif of α-Li 2 IrO 3 is closely related, but not identical to LiCoO 2 .…”

Section: Introductionmentioning

confidence: 99%

“…10,11 Hence the slight occupational disorder between Li + and Ir 4+ in the layers, which was introduced to the structural model during the refinement, could be an artefact from daubed reflection intensities due to diffraction line broadening by the appearance of stacking faults. 10,11 The overall structural motif of α-Li 2 IrO 3 is closely related, but not identical to LiCoO 2 . 12 Due to the honeycomb ordering of the 2 Ir-sites and the Li-site within the layer of Li 2 IrO 3 and the associated monoclinic distortion of the unit cell of α-Li 2 IrO 3 the anion sublattice exhibits an ABCA′B′C′A″B″ C″…, stacking ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Solution of the heavily stacking faulted crystal structure of the honeycomb iridate H₃LiIr₂O₆

et al. 2017

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A powder sample of pure H 3 LiIr 2 O 6 was synthesized from α-Li 2 IrO 3 powder by a soft chemical replacement of Li + with H + . The crystal structure of H 3 LiIr 2 O 6 consists of sheets of edge sharing LiO 6 -and IrO 6 -octahedra forming a honeycomb network with layers stacked in a monoclinic distorted HCrO 2 type pattern. Heavy stacking faulting of the sheets is indicated by anisotropic peak broadening in the X-ray powder diffraction (XRPD) pattern. The ideal, faultless crystal structure was obtained by a Rietveld refinement of the laboratory XRPD pattern while using the LiIr 2 O 6 3− -layers of α-Li 2 IrO 3 as a starting model. The low radial distances of the PDF function, derived from synchrotron XRPD data, as constraints to stabilize the structural refinement. DIFFaX-simulations, structural considerations, high radial distances of the PDF function and a Rietveld compatible global optimization of a supercell were employed to derive a suitable faulting model and to refine the microstructure using the experimental data. We assumed that the overall stacking pattern of the layers in the structure of H 3 LiIr 2 O 6 is governed by interlayer O-H⋯O contacts.From the constitution of the layers, different stacking patterns with similar amounts of strong O-H⋯O contacts are considered. Random transitions among these stacking patterns can occur as faults in the crystal structure of H 3 LiIr 2 O 6 , which quantitatively describe the observed XRPD.

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Fundamental Insights from a Single‐Crystal Sodium Iridate Battery

Tepavcevic

Zheng

Hinks

et al. 2020

Advanced Energy Materials

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Electrochemically driven chemical transformations play the key role in controlling storage of energy in chemical bonds and subsequent conversion to power electric vehicles and consumer electronics. The promise of coupling anionic oxygen redox with cationic redox to achieve a substantial increase in capacities has inspired research in a wide range of electrode materials. A key challenge is that these studies have focused on polycrystalline materials, where it is hard to perform precise structural determinations, especially related to the location of light atoms. Here a different approach is utilized and a highly ordered single crystal, Na2−xIrO3 is harnessed, to explore the role of defects and structural transformations in layered transition metal oxide materials on redox‐activity, capacity, reversibility, and stability. Within a combined experimental and theoretical framework, it is demonstrated that 1) it is possible to cycle Na2−xIrO3, offering proof of principle for single‐crystal based batteries 2) structural phase transitions coincide with Ir 4+/Ir 5+ redox couple with no evident contribution from anionic redox 3) strong irreversibility and capacity fade observed during cycling correlates with the Na + migration resulting in progressive growth of an electrochemically inert O3‐type NaIrO3 phase.

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New honeycomb iridium(v) oxides: NaIrO₃ and Sr₃CaIr₂O₉

Cited by 40 publications

References 37 publications

Structural evolution and electronic properties of (Sr1−xCax)2−yIrO4+

Structural evolution and electronic properties of (Sr1−xCax)2−yIrO4+

Solution of the heavily stacking faulted crystal structure of the honeycomb iridate H₃LiIr₂O₆

Fundamental Insights from a Single‐Crystal Sodium Iridate Battery

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New honeycomb iridium(v) oxides: NaIrO3 and Sr3CaIr2O9

Cited by 40 publications

References 37 publications

Structural evolution and electronic properties of (Sr1−xCax)2−yIrO4+

Structural evolution and electronic properties of (Sr1−xCax)2−yIrO4+

Solution of the heavily stacking faulted crystal structure of the honeycomb iridate H3LiIr2O6

Fundamental Insights from a Single‐Crystal Sodium Iridate Battery

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Product

Resources

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New honeycomb iridium(v) oxides: NaIrO₃ and Sr₃CaIr₂O₉

Solution of the heavily stacking faulted crystal structure of the honeycomb iridate H₃LiIr₂O₆