Metal–insulator transition in compounds

Kato, Masaki; Tani, Yasuo; Imamura, Takashi; Hirota, Ken; Yoshimura, Kazuyoshi

doi:10.1016/j.physb.2007.10.135

Cited by 6 publications

(1 citation statement)

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“…Masaki KATO, Kazuya IWAMOTO, Yuki IWAKURA, Ken HIROTA, Angel AREVALO-LOPEZ and John Paul ATTFIELD moment on the ruthenium atoms 8,20) . In order to clarify the transport behaviors of pyrochlore ruthenates near the boundary of the metal- 21,22) . Especially, we report Pb-Eu system from viewpoints of (1) magnetic and electric properties, (2) microscopic structural parameters and (3) strongly- Those with higher contents of Ca were exposed to HIP (hot isostatic pressing) treatment at 1000°C under 196 MPa of O 2 20%/ Ar 80% gas atmosphere for 4 hours after the heat treatment at 900°C in air for 24 hours.…”

Section: Introductionmentioning

confidence: 99%

Metal-insulator Crossover in Pb-Ru Based Oxides with Pyrochlore-type Structure

Kato

Iwamoto

Iwakura

et al. 2018

J. Jpn. Soc. Powder Powder Metallurgy

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Synthesis and physical properties of the Pb-Ru based pyrochlores Pb 2−x M x Ru 2 O 7−δ (M = Eu and Ca) have been studied. For Pb-Eu solid solution Pb 2−x Eu x Ru 2 O 7−δ , single phases were successfully synthesized by the solid-state reaction. Magnetic susceptibility measurements indicated the magnetic transition due to spin-glass freezing in the samples with x ≥ 0.8. From electric resistivity measurements, a crossover from metallic to semiconducting behaviors was observed in the range of 0.6 ≤ x ≤ 0.8. In the metallic region, normalized electric resistivity was found to be almost proportional to T 2 , indicating the strongly-correlated electron behaviors. The crossover between insulating and metallic phases can be caused by the strong electron-electron couplings between the itinerant 4d electrons. For Pb-Ca solid solution Pb 2−x Ca x Ru 2 O 7−δ , single phases were obtained for x ≤ 0.6 samples by heat treatments in air. Pb 2−x Ca x Ru 2 O 7−δ samples with 0.8 ≤ x ≤ 1.6 were successfully synthesized under high oxygen pressures. Lattice parameter of Pb 2−x Ca x Ru 2 O 7−δ compounds was found to decrease with Ca content x, resulting in the positive chemical pressure. As a result of electric resistivity measurements, the samples with 0.0 ≤ x ≤ 1.0 showed the metallic behaviors.

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Section: Introductionmentioning

confidence: 99%