Synthesis and Crystal Structure of Rb3AgO2

Sofin, Mikhail; Friese, Karen; Nuß, Jürgen; Peters, E.‐M.; Jansen, Martin

doi:10.1002/1521-3749(200211)628:11<2500::aid-zaac2500>3.0.co;2-l

Cited by 5 publications

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“…Micro-crystalline powder samples of NaCu 2 O 2 were synthesized via the azide/nitrate route in specially designed containers [12,13,14]. The starting materials were milled, pressed in pellets under 10 5 N, dried in vacuum (10 −3 mbar) at 150 • C for 12 h, and placed in an argon atmosphere in a tightly closed steel container provided with a silver inlay.…”

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Helicoidal magnetic order in the spin-chain compoundNaCu2O2

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We report susceptibility, specific heat, and neutron diffraction measurements on NaCu2O2, a spin-1/2 chain compound isostructural to LiCu2O2, which has been extensively investigated. Below 12 K, we find a long-range ordered, incommensurate magnetic helix state with a propagation vector similar to that of LiCu2O2. In contrast to the Li analogue, substitutional disorder is negligible in NaCu2O2. We can thus rule out that the helix is induced by impurities, as was claimed on the basis of prior work on LiCu2O2. A spin Hamiltonian with frustrated longer-range exchange interactions provides a good description of both the ordered state and the paramagnetic susceptibility.PACS numbers: 75.10. Pq, 75.40.Cx, 75.25.+z Copper oxides are excellent model systems for lowdimensional spin-1/2 quantum antiferromagnets. In particular, copper oxides with magnetic backbones comprised of chains of CuO 4 squares have been shown to exhibit quasi-one-dimensional behavior. Two classes of copper oxide spin chain materials are known. Compounds in which adjacent squares share their corners are excellent realizations of the one-dimensional (1D) spin-1/2 Heisenberg Hamiltonian [1, 2, 3]. Linear Cu-O-Cu bonds along the spin chains give rise to a large antiferromagnetic nearest-neighbor exchange coupling. In compounds built up of edge-sharing squares, on the other hand, the Cu-O-Cu bond angle is nearly 90 • , so that the nearest-neighbor coupling is more than an order of magnitude smaller [4]. Because of the anomalously small nearest-neighbor coupling, longer-range frustrating exchange interactions have a pronounced influence on the physical properties of these materials. Edge-sharing copper oxides thus provide uniquely simple model systems to test current theories of spin correlations in frustrated quantum magnets.At low temperatures, the ground state of edge-sharing copper oxides is either a 3D-ordered antiferromagnet [5,6,7] or a spin-Peierls state [8], depending on whether interchain exchange interactions or spin-phonon interactions are dominant. In the former case, the magnetic order is almost always collinear. An interesting exception was recently discovered in LiCu 2 O 2 [9, 10, 11], which undergoes a transition to a magnetic helix state at low temperatures. While such a state is expected for classical spin models with frustrating interactions, quantum models predict a gapped spin liquid state in the range of exchange parameters that was claimed to describe the spin system in LiCu 2 O 2 . Since the ionic radii of Li + and Cu 2+ are similar, chemical disorder was identified as a possible solution to this puzzle. Indeed, a chemical analysis of the sample used in the neutron scattering study of Ref. [11] showed that about 16% of the Cu 2+ ions in the spin chains were replaced by nonmagnetic Li + impurities. Since even much lower concentrations of nonmagnetic impurities are found to induce magnetic long-range order in other quasi-1D spin-gap systems, the authors of Ref.[11] attributed the unexpected helix state to the Here we report magnet...

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Helicoidal magnetic order in the spin-chain compoundNaCu2O2

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“…The starting materials were mixed in the ratio required according to (1), ground thoroughly in an agate mortar, pressed into pellets (Ø = 6 mm) under 10 5 N, dried in vacuum (10 -3 mbar) at 400 K for 12 h and placed under argon into a tightly closed steel vessel, provided with a silver inlay (Sofin, Friese et al, 2002;.…”

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Structure of RbFeO₂, refined from a reticular pseudomerohedrally twinned crystal with six domains

Nuß

Ali

Jansen

2007

Acta Crystallogr Sect B

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RbFeO(2), rubidium oxoferrate, crystallizes as an orthorhombic structure. The crystals under investigation were composed of six individuals representing reticular pseudomerohedral twins with a pseudocubic twin lattice of index 4 because of the approximate equations a(8)(1/2) = b(2)(1/2) = c. The compound is isostructural with KFeO(2) (KGaO(2) type of structure) and is composed of [FeO(4/2)](-) corner-sharing tetrahedra, forming a three-dimensional cristobalite-like network, with Rb(+) ions occupying its interstices.

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Synthesis and Crystal Structure of Rb₃AgO₂.

Sofin¹,

Friese²,

Nuß³

et al. 2002

ChemInform

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structure structure (solids and liquids) D 2000 -006Synthesis and Crystal Structure of Rb 3 AgO 2 . -The title compound is prepared by the azide/nitrate route starting with a stoichiometric mixture of Ag 2 O, RbN 3 , and RbNO 3 (silver crucible, argon, 450 • C, 50 h). Rb 3 AgO 2 crystallizes in the orthorhombic space group P2 1 2 1 2 1 with Z = 16 and is isostructural with K 3 AgO 2 . The Ag atoms are linearly coordinated by O atoms and Rb has pseudo-tetrahedral coordination. -(SOFIN, M.; FRIESE, K.; NUSS, J.; PETERS, E. M.; JANSEN, M.; Z.

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Synthesis and Crystal Structure of Rb3AgO2

Cited by 5 publications

References 18 publications

Helicoidal magnetic order in the spin-chain compoundNaCu2O2

Helicoidal magnetic order in the spin-chain compoundNaCu2O2

Structure of RbFeO₂, refined from a reticular pseudomerohedrally twinned crystal with six domains

Synthesis and Crystal Structure of Rb₃AgO₂.

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Synthesis and Crystal Structure of Rb3AgO2

Cited by 5 publications

References 18 publications

Helicoidal magnetic order in the spin-chain compoundNaCu2O2

Helicoidal magnetic order in the spin-chain compoundNaCu2O2

Structure of RbFeO2, refined from a reticular pseudomerohedrally twinned crystal with six domains