Pb2M2O7−x (M = Ru, Ir, Re) — Preparation and properties of oxygen deficient pyrochlores

Longo, J.M.; Raccah, P. M.; Goodenough, John B.

doi:10.1016/0025-5408(69)90056-7

Cited by 174 publications

(72 citation statements)

References 16 publications

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“…The Pb-and Re-containing complex oxide with the pyrochlore structure was prepared earlier by solid state reaction of PbO and ReO (1). It was assumed on the basis of lattice parameters that Pb Re O has an anion-deficient pyrochlore-type structure but to date no attempts have been made to determine the crystal structure and the oxygen content of Pb Re O .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Study of Pb2Re2O7−xPyrochlores

Abakumov

Shpanchenko

Антипов

et al. 1998

Journal of Solid State Chemistry

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Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Study of Pb2Re2O7−xPyrochlores

Abakumov

Shpanchenko

Антипов

et al. 1998

Journal of Solid State Chemistry

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“…[13][14][15][16] Pb 2 Ru 2 O 7-δ has a pyrochlore-type structure with some oxygen vacancies, and shows high electronic conductivity. [17][18][19][20][21][22][23][24][25][26] Horowitz et al 20 have firstly reported that Pb 2 Ru 2 O 7-δ which is prepared by co-precipitation method in aqueous solution and post heat-treatment at 300-750…”

mentioning

confidence: 99%

Effects of Oxygen Vacancies and Reaction Conditions on Oxygen Reduction Reaction on Pyrochlore-Type Lead-Ruthenium Oxide

Fujii

Satô

Takase

2014

J. Electrochem. Soc.

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A series of pyrochlore-type lead-ruthenium oxide (Pb 2 Ru 2 O 7-δ ) containing various amounts of oxygen vacancies was prepared by varying the heat-treatment temperature, and the oxygen reduction reaction (ORR) activity as well as the electrochemical redox property in acid and alkaline solution was evaluated using rotating disk electrode. The specific ORR activity was increased with increasing the amount of oxygen vacancies, and linearly correlated to the charge amount of electrochemical redox of Pb 2 Ru 2 O 7-δ both in acid and alkaline solution. We concluded that the surface oxygen vacancy participates in the electrochemical redox of Pb 2 Ru 2 O 7-δ , and at the same time, behaves as the active site for ORR. The ORR activity in alkaline solution was much higher than that in acid solution, possibly because of the difference of the facility of electrochemical desorption of adsorbed oxygen species in the ORR process. Additionally, the effect of humidity on the ORR activity was investigated by single cell test. Proton exchange membrane fuel cells (PEMFCs) are promising alternative power sources for home co-generation system and transportation applications due to advantages such as low emission and high efficiency. There are, however, still many problems remaining for widespread commercialization of PEMFCs. In the current PEMFCs, platinum based catalyst is used as the cathode electrocatalyst for oxygen reduction reaction (ORR). From the view of cost and availability, alternative electrocatalyst to platinum is strongly required. While many types of non-platinum electrocatalyst have been reported, such as metal-oxides, metal macrocyclic complex, metal chalcogenides, and nitrogen-containing carbon, none of them has been applied to practice due to poor performance or durability. 1-12We have been focusing on lead-ruthenium oxide (Pb 2 Ru 2 O 7-δ ) as a candidate of non-platinum electrocatalyst for ORR. [13][14][15][16] Pb 2 Ru 2 O 7-δ has a pyrochlore-type structure with some oxygen vacancies, and shows high electronic conductivity. [17][18][19][20][21][22][23][24][25][26] Horowitz et al. 20 have firstly reported that Pb 2 Ru 2 O 7-δ which is prepared by co-precipitation method in aqueous solution and post heat-treatment at 300-750• C shows high ORR activity in alkaline solution. Afterwards, several researches aimed at application of Pb 2 Ru 2 O 7-δ to electrochemical devices such as fuel cell, metal-air battery and oxygen sensor have been conducted. 20,21,[27][28][29][30][31][32][33][34] For example, Goodenough et al. 31,35 have reported that Pb 2 Ru 2 O 7-δ shows ORR activity and high stability not only in alkaline solution but also in acid solution and proton exchange membrane such as Nafion. Also, we have found that partial substitution of other cations such as Bi, In, or Sb with Pb site in Pb 2 Ru 2 O 7-δ have a positive effect on the ORR activity.13 Nevertheless, the ORR activity of Pb 2 Ru 2 O 7-δ is needed to be drastically enhanced for practical use as the cathode electrocatalyst of PEMFC. For this purpose, it ...

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“…Here, the X site is partially or fully occupied by an oxygen atom. The space group of pyrochlore was originally suggested to be Fd3m [54,55], in which the X site is randomly and partially occupied. Later investigation by a powder neutron diffraction experiment [56] showed that the space group is F43m; in this model vacancies in the X site are ordered.…”

Section: A 4 and B 4 -Clusters In Ordered Pyrochlore Structuresmentioning

confidence: 99%

Universal mechanism of tetrahedral metal cluster formation in structures with breathing pyrochlore sublattices

Таланов¹,

Таланов²

2017

Nanosystems: Phys. Chem. Math.

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A universal mechanism of tetrahedral metal cluster formation in crystal with geometrically frustrated pyrochlore sublattices is proposed. It has been shown that the critical irreducible representation τ , which generated the formation of metal clusters in non-centrosymmetrical F43m-phases from high symmetry phases with Fd3m space group, is a one dimensional irreducible representation κ 11 (τ 4 (A 2u )) (in Kovalev notation). The structural theory of metal cluster formation based on group theoretical calculations was published earlier for the case of A-ordered spinel. In this work, the theory is generalized in the case of any high symmetry Fd3m structures that include pyrochlore sublattices. We presented a brief review of such structures and mechanisms of the tetrahedral metal cluster formation. The existence of so called "breathing" pyrochlore sublattices in ordered phases is predicted theoretically. The groups of atoms, between which bond clusters, are found. These groups of atoms define electron correlation effects. Examples of tetrahedral metal cluster formation in ordered spinels, ordered lacunar spinels, ordered Laves phases (MgCu 4 Sn structural type) and ordered pyrochlore are considered. The theoretical results are confirmed by the known experimental facts.

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Pb2M2O7−x (M = Ru, Ir, Re) — Preparation and properties of oxygen deficient pyrochlores

Cited by 174 publications

References 16 publications

Synthesis and Structural Study of Pb2Re2O7−xPyrochlores

Synthesis and Structural Study of Pb2Re2O7−xPyrochlores

Effects of Oxygen Vacancies and Reaction Conditions on Oxygen Reduction Reaction on Pyrochlore-Type Lead-Ruthenium Oxide

Universal mechanism of tetrahedral metal cluster formation in structures with breathing pyrochlore sublattices

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