Synthesis and properties of Ba3NaRu2O9− and Ba3(Na, R)Ru2O9− (R=rare earth) crystals

Samata, H.; Kai, Masahiro; Uchida, Takayuki; Ohtsuka, Masao; Tanaka, Gengo; Sawada, S.; Taniguchi, Takashi; Nagata, Y.

doi:10.1016/s0925-8388(02)00990-8

Cited by 12 publications

(7 citation statements)

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“…The oxidation state situation in Tl 2 Ru 2 O 7 is very complex because of the strong contribution of both Ru 4d and Tl 6s states at the Fermi level. Structural studies have suggested that a charge ordering transition may occur in Ba 3 NaRu 2 O 9 at 225 K. 36 However, subsequent electrical resistivity measurements show no increase resistivity at or just below 225 K. 37 It thus appears that Pb 3 Rh 7 O 15 is the only known candidate for a classical Verwey-type transition in an oxide where the cation is not a 3d cation.…”

Section: Discussionmentioning

confidence: 99%

Possible Verwey-Type Transition in Pb₃Rh₇O₁₅

et al. 2009

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Crystals of the mixed-valence compound Pb3Rh4 3+Rh3 4+O15 have been grown in a PbO flux. These hexagonal crystals show an isotropic electrical resistivity of about 1 × 10−3 ohm cm at room temperature. This resistivity slowly increases with decreasing temperature until 185 K, where the resistivity begins increasing more rapidly as temperature is further decreased. Specific heat measurements on polycrystalline Pb3Rh7O15 show a sharp, lambda-shaped peak at 185 K. Magnetic susceptibility and thermopower measurements on Pb3Rh7O15 also show a discontinuity at about 185 K. Structural analyses of X-ray diffraction data obtained above and below 185 K indicate that a change in space group has occurred at 185 K. It is likely that the transition at 185 K is related to a change in charge modulation. The phase transition at 185 K fades away as Bi is substituted for Pb in Pb3Rh7O15.

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Section: Discussionmentioning

confidence: 99%

Possible Verwey-Type Transition in Pb₃Rh₇O₁₅

et al. 2009

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“…In Ba3MRu2O9, when M is a non-magnetic monovalent cation (eg. Li or Na), the total number of electrons donated by the Ru to the oxygens in a Ru2O9 dimer is 11 [63][64][65] . (The Ru can be considered formally as a 1:1 mixture of Ru 5+ and Ru 6+ , but "where's the charge, really?"…”

Section: Dimer-based Hexagonal Perovskitesmentioning

confidence: 99%

Hexagonal Perovskites as Quantum Materials

Nguyen

Cava

2020

Chem. Rev.

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Hexagonal oxide perovskites, in contrast to the more familiar perovskites, allow for face-sharing of metal-oxygen octahedra or trigonal prisms within their structural frameworks. This results in dimers, trimers, tetramers, or longer fragments of chains of face-sharing octahedra in the crystal structures, and consequently in much shorter metal-metal distances and lower metal-oxygen-metal bond angles than are seen in the more familiar perovskites. The presence of the face-sharing octahedra can have a dramatic impact on magnetic properties of these compounds, and dimer-based materials, in particular, have been the subjects of many quantum-materials-directed studies in materials physics. Hexagonal oxide perovskites are of contemporary interest due to their potential for geometrical frustration of the ordering of magnetic moments or orbital occupancies at low temperatures, which is especially relevant to their significance as quantum materials. As such, several hexagonal oxide perovskites have been identified as potential candidates for hosting the quantum spin liquid state at low temperatures. In our view, hexagonal oxide perovskites are fertile ground for finding new quantum materials. This review briefly describes the solid state chemistry of many of these materials.

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“…In its archetypical formula ABO 3 , ''A'' commonly represents a larger, electropositive cation, while ''B'' is smaller and bears a higher charge. If charge or size combinations of cations are incompatible with the ideal perovskite structure, the structure has many options to flexibly respond by adopting lower symmetries [1,2] or by allowing for mixed or deficient atomic site occupancies [3,4]. Partial chemical substitution of the B cation may alter the basic formula ABO 3 sizeably to more complex compositions like A 2 BB 0 O 6 and A 3 BB 0 2 O 9 .…”

Section: Introductionmentioning

confidence: 99%