Bismuth Ruthenium Oxides. Neutron Diffraction and Photoelectron Spectroscopic Study of Bi2Ru2O7 and Bi3Ru3O11

Abstract

The structures of Bi3Ru3O11, a = 9.3050(2)Ǻ, Pn3, and Bi2Ru2O7, a = 10.2957(1)Ǻ, Fd3m, have been redetermined by Rietveld analysis of powder neutron diffraction data. For both compounds there is no evidence for appreciable oxygen non- stoichiometry . X-Ray photoelectron spectra of both compounds show unusual line shapes. In the case of Bi3Ru3O11 this is a result of the mixed valency and surface oxidation. In Bi2Ru2O7 final state effects appear to be important.

Structural and Bonding Trends in Ruthenium Pyrochlores

“…At the same time the decrease in r 3ϩ A for the 8 ruthenate pyrochlores A 2 Ru 2 O 7Ϫy , A ϭ Pr, x lessens the apparent compression in the AO 8 scaleheNd, Y, Tb, Yb, Bi, Tl(LT), and Tl(HT), the structures of dron, the two A-O(2) bonds along the Ϫ3 axis are noticewhich have been determined using powder neutron diffrac-ably shorter than the other six, equidistant, A-O(1) distion (3,15,25). It is immediately apparent from this figure tances (Table 2).…”

“…Bi 2 Ru 2 O 7 was reported by Facer et al (3) in which the Ru-O distance was found to be 1.983 Å and the RuAll structural refinements were performed using a version of Hill and Howard's program LHPM (20), modified O-Ru angle 133.14Њ. Using the criteria of Kanno et al, these data suggest that this metallic oxide should in fact for a personal computer.…”

“…e.g., Y 2 Ru 2 O 7 . While there have been a number of atDuring the past 15 years there has been considerable tempts to correlate the structural and electronic properties growth in the number of reported studies on pyrochlore-of the ruthenate pyrochlores (3)(4)(5)(11)(12)(13) only for a handtype oxides as a consequence of the stability and diverse ful of these materials are precise structural data available. physical properties of these materials.…”

“…The HRNPD is equipped with a bank of 64 individual 3 He for semiconducting oxides. The effect of smaller Ru-O distances and larger Ru-O-Ru angles is to increase detectors, and data were collected at room temperature between 10Њ and 155Њ in 0.05Њ steps.…”

Structural Studies of the Metal–Nonmetal Transition in Ru Pyrochlores

“…It is not uncommon for transition metal pyrochlores to exhibit a metal}nonmetal transition. A further example of the variable physical properties of the pyrochlores comes from studies of Bi Ru O \ by Carbonio and co-workers (17) who extended our previous work (18) and showed that it is possible to control the oxygen stoichiometry, and hence the structure and conductivity of Bi Ru O \ , by altering the annealing conditions. In parallel with these studies on unsubstituted pyrochlores, Kanno (22).…”