Structural Studies of the Metal–Nonmetal Transition in Ru Pyrochlores

Photoemission and x-ray absorption spectroscopy studies on cubic pyrochlore ruthenatesBi2−xYxPark1, Kim2, Noh3 et al. 2004Phys. Rev. B291110View full textAdd to dashboardCite

“…8 Similar to the perovskite ruthenates, some authors argued a strong relationship between the electrical properties and the crystal structure considering the Ru-O bond length versus Ru-O-Ru bonding angle diagram. [9][10][11][12][13] However, unlike the 3d transition-metal compounds where many physical properties were described by a manybody theory taking into account the 3d electron correlation, 14 -16 only a few systems such as perovskite and pyrochlore structure ternary ruthenium oxides were studied in this respect among 4d electron systems. 17,[19][20][21][22] Cox et al performed early high-resolution ultraviolet photoemission spectroscopy ͑UPS͒, 23 and suggested from the variation in the density of states at the Fermi level (E f ) an increase in U/W (U is electron correlation energy, W is one-electron bandwidth͒ in the series Bi 2 Ru 2 O 7 Ͻ SrRuO 3 Ͻ CaRuO 3 Ͻ Y 2 Ru 2 O 7 and progressive decrease in the transfer integral that determines the conduction bandwidth.…”

Novel Y2−xPrxRu2O7 (x=0–2) Pyrochlore Oxides Prepared Using a Soft Chemistry Route and their Electrical Properties

“…The width of the t 2g ‐block bands of A 2 Ru 2 O 7− y increases with increasing Ru–O–Ru bond angle and decreasing Ru–O distance. When Ru–O–Ru angle is larger than 133° and the bond distance Ru–O is less than 2 Å, the bandwidth becomes greater than a critical value and A 2 Ru 2 O 7− y shows metallic behavior 7–10 …”

Structural and magnetic properties of the (Bi2−xPrx)Ru2O7 pyrochlore solid solution (0≤x≤2)

“…Magnetic properties were reported only for Ln = Nd [9]. We also note that in the previous study of Bi 2−x Ln x Ru 2 O 7 systems [9], no XRD diagrams were shown, and that the interatomic distances obtained for unsubstituted Bi 2 Ru 2 O 7 disagree with those reported in other studies [10][11][12]. The lack of reports of magnetic properties and the inconsistencies in interatomic distances (and certainly angles) in the previous studies of Bi 2−x Pr x Ru 2 O 7 prompted us to undertake a detailed crystal chemical and magnetic study of this system, the results of which are presented in this paper.…”

“…4e) decreases with increasing x and indeed crosses the boundary recently pre- Table 2 Selected bond lengths (Å) and angles ( • ) in the Bi2−xPrxRu2O7 series. dicted for the occurrence of a metal-non-metal transition [11]. (3) gets larger.…”