Ferromagnetic Order from p-Electrons in Rubidium Oxide

Riyadi, Syarif; Giriyapura, Shivakumara; Groot, R.A. de; Caretta, Antonio; Loosdrecht, P.H.M. van; Palstra, Thomas; Blake, Graeme R.

doi:10.1021/cm103433r

Cited by 26 publications

(26 citation statements)

References 60 publications

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“…The 18 O exchange experiments reported at the end of this publication further support the presence of mobile

V_{O_{2}}^{•}

. It is noteworthy that recently a RbO 1.72 phase was reported to have a structure that can be regarded as RbO 2 containing a high concentration of anion vacancies (no superstructure peaks related to ordering of the vacancies were observed) …”

Section: Resultssupporting

confidence: 73%

Electrical Transport and Oxygen Exchange in the Superoxides of Potassium, Rubidium, and Cesium

Gerbig

Merkle

Maier

2015

Adv Funct Materials

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Conductivity, ionic transference number, and chemical diffusion coeffi cients are determined for KO 2 , RbO 2 , and CsO 2 . Based on such results, a defectchemical model is constructed. These superoxides are found to exhibit a total conductivity in the range of 3 × 10 -7 to 5 × 10 -5 S cm -1 at 200 °C with contributions from ionic and electronic carriers. The ionic conductivity is caused by alkali interstitials and superoxide vacancies as mobile defects, and is found to exceed the n-type electronic conductivity. 18 O isotope exchange on powder samples (monitoring the gas phase composition) shows that essentially all oxygen can be exchanged. At high p O 2 this largely occurs without breaking of the O-O bond-indicating a suffi cient mobility of molecular superoxide species in the solid-and with an effective rate constant that is much higher than for other large-bandgap mixed conducting materials such as SrTiO 3 .

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“…The 18 O exchange experiments reported at the end of this publication further support the presence of mobile

V_{O_{2}}^{•}

Section: Resultssupporting

confidence: 73%

Electrical Transport and Oxygen Exchange in the Superoxides of Potassium, Rubidium, and Cesium

Gerbig

Merkle

Maier

2015

Adv Funct Materials

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“…[11][12][13][14][15] These counter cations have small ionic radii and high charge densities, i.e. they were "hard acids" to give strong cation-anion interactions and melting points much higher than RT.…”

Section: Superoxide Anion Omentioning

confidence: 99%

An Ionic Liquid State Composed of Superoxide Radical Anions and Crownether-Coordinated Potassium Cations

Kitada

Ishikawa

Fukami

et al. 2017

J. Electrochem. Soc.

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We report an "ionic liquid state" substance composed of superoxide radical anions (O 2 -) and crownether-coordinated potassium cations. A binary mixture of 18-crown-6-ether (18C6) and potassium superoxide (KO 2 ) becomes liquid above ca. 38 • C. The coordination of 18C6 to K + and the presence of O 2 -were confirmed in the liquid state by Raman spectroscopy measurements. Below 38 • C, however, the 18C6-KO 2 mixture does not form a complex but undergoes phase separation to parent phases of solid 18C6 and KO 2 , because the ion-dipole interaction between K + and 18C6 is overwhelmed by the ion-ion interaction between K + and O 2 -. In other words, the pair of O 2 -and 18C6-coordinated K + only appears above the melting point of pure 18C6, to form an "ionic liquid state". Among radical-containing ionic liquids, the liquid 18C6-KO 2 mixture has high fluidity and comparable conductivity. , aprotic solvents were used to dissolve KO 2 . For example, a highly polar aprotic solvent, dimethylsulfoxide (DMSO), was used with a cyclic ionophore dicyclohexyl-18-crown-6-ether (D18C6) to prepare KO 2 solution. 5The highest concentration of O 2 -in organic solution, however, is only 0.15 mol dm -3 in D18C6-containing DMSO solution, i.e. KO 2 :D18C6:DMSO = 1:2:100 by mole.5 O 2 -solutions can also be obtained chemically or electrochemically in aprotic solvents including ionic liquids, but the concentrations are small. 6-10 Therefore, drastic increase in superoxide radical concentration is of interest; for this purpose, designing novel superoxide radical compounds in liquid state is necessary.Examples of known superoxides are alkaline and alkaline-earth metal superoxides, of which magnetism have attracted attention. 11-15These counter cations have small ionic radii and high charge densities, i.e. they were "hard acids" to give strong cation-anion interactions and melting points much higher than RT. From this viewpoint, larger counter cations need to be designed. There are several superoxides using large cations such as quaternary ammonium cations, but their liquid properties are missing due to rapid decomposition. 16,17 An alternative approach for novel "superoxide liquids" may be coordination of metal cations by ethers. This is because ethers were judged to be more stable to O 2 -attack than organic carbonates, 18 which attracted attention as metal-air battery electrolytes. [19][20][21][22][23] It is also because ethers have been used to prepare so-called "solvate ionic liquids", where ether-coordinated metal cations are component cations. 24-28Our preliminary results showed that an equimolar mixture of 18-crown-6-ether (18C6) and potassium superoxide (KO 2 ) becomes liquid above 41• C, without sizable decomposition of O 2 -, while equimolar mixtures of KO 2 and other ethers such as glymes and D18C6 rapidly decomposed. 29 In this work, we study the detailed physico- * Electrochemical Society Member. z E-mail: kitada.atsushi.3r@kyoto-u.ac.jp chemical properties of 18C6-KO 2 mixture: in addition to our earlier work, 29 we performed ...

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“…16 Antiferromagnetic coupling [17][18][19] lends itself more readily to geometric frustration than ferromagnetic coupling, explaining the limited number of metallic, ferromagnetically coupled cluster-glass systems. Several cases are known, where a cluster-glass state arises from a ferromagnetic ground state in metal oxides, [20][21][22][23] 26,27 dynamic fluctuations of crystalfield levels have been suggested as the underlying mechanism for the magnetic frustration in PrRhSn 3 , 28 based on the fact that neither site disorder nor geometric frustration is present in this compound. The current study shows that the addition of Er 3+ local moments in the ferromagnet Sc 3.1 In induces a cluster-glass state in (Sc 1−x Er x ) 3.1 In (0 < x 0.10), while the Weiss-like temperature θ , a measure of the local-to-itinerant moment coupling, remains positive.…”

Section: Introductionmentioning

confidence: 99%

Cluster-glass behavior induced by local moment doping in the itinerant ferromagnet Sc3.1In

Svanidze

Morosan

2013

Phys. Rev. B

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In the presented work, Sc 3.1 In, a weak itinerant ferromagnet with no magnetic constituents, is doped with Er 3+ local moment ions, to form (Sc 1−x Er x ) 3.1 In. As x increases, the Weiss-like temperature θ stays positive and nearly triples up to x = 0.10. Moreover, Er doping of as little as x = 0.02 induces a cluster-glass state, which persists up to x = 0.10, as evidenced by dc and ac susceptibility measurements, and confirmed by the Vogel-Fulcher analysis.

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Ferromagnetic Order from p-Electrons in Rubidium Oxide

Cited by 26 publications

References 60 publications

Electrical Transport and Oxygen Exchange in the Superoxides of Potassium, Rubidium, and Cesium

Electrical Transport and Oxygen Exchange in the Superoxides of Potassium, Rubidium, and Cesium

An Ionic Liquid State Composed of Superoxide Radical Anions and Crownether-Coordinated Potassium Cations

Cluster-glass behavior induced by local moment doping in the itinerant ferromagnet Sc3.1In

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