Orbital ordering and valence states in (La1+xCa1-x)CoRuO6 double perovskites

Jan-willem Bos; J. Attfield; Ting-shan Chan; Ru-shi Liu; Ling-yun Jang

doi:10.1103/PhysRevB.72.014101

Orbital ordering and valence states in (La₁+_xCa_1-x)CoRuO₆ double perovskites

Jan-willem Bos, J. Attfield, Ting-shan Chan, Ru-shi Liu, Ling-yun Jang

Research output: Contribution to journal › Article › peer-review

Abstract

(La_1+xCa_1−x)CoRuO₆ double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO₆ structure has been investigated between 4 and 1073 K using neutron powder diffraction. The cell b axis shows a crossover from negative to positive thermal expansion at T≈425 K, which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co²⁺ t_2g holes. Ru valence states of doped (La_1+xCa_1−x)CoRuO₆ (−0.25≤x≤0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru⁵⁺→Ru⁴⁺ while hole-doped x≤0 compositions have a constant Ru⁵⁺ state. These observations support a proposed asymmetric doping model.

Original language	English
Article number	014101
Number of pages	5
Journal	Physical review B
Volume	72
Issue number	1
Early online date	1 Jul 2005
DOIs	https://doi.org/10.1103/PhysRevB.72.014101
Publication status	Published - 2005

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title = "Orbital ordering and valence states in (La1+xCa1-x)CoRuO6 double perovskites",

abstract = "(La1+xCa1−x)CoRuO6 double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO6 structure has been investigated between 4 and 1073 K using neutron powder diffraction. The cell b axis shows a crossover from negative to positive thermal expansion at T≈425 K, which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co2+ t2g holes. Ru valence states of doped (La1+xCa1−x)CoRuO6 (−0.25≤x≤0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru5+→Ru4+ while hole-doped x≤0 compositions have a constant Ru5+ state. These observations support a proposed asymmetric doping model.",

author = "Jan-willem Bos and J. Attfield and Ting-shan Chan and Ru-shi Liu and Ling-yun Jang",

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T1 - Orbital ordering and valence states in (La1+xCa1-x)CoRuO6 double perovskites

AU - Bos, Jan-willem

AU - Attfield, J.

AU - Chan, Ting-shan

AU - Liu, Ru-shi

AU - Jang, Ling-yun

PY - 2005

Y1 - 2005

N2 - (La1+xCa1−x)CoRuO6 double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO6 structure has been investigated between 4 and 1073 K using neutron powder diffraction. The cell b axis shows a crossover from negative to positive thermal expansion at T≈425 K, which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co2+ t2g holes. Ru valence states of doped (La1+xCa1−x)CoRuO6 (−0.25≤x≤0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru5+→Ru4+ while hole-doped x≤0 compositions have a constant Ru5+ state. These observations support a proposed asymmetric doping model.

AB - (La1+xCa1−x)CoRuO6 double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO6 structure has been investigated between 4 and 1073 K using neutron powder diffraction. The cell b axis shows a crossover from negative to positive thermal expansion at T≈425 K, which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co2+ t2g holes. Ru valence states of doped (La1+xCa1−x)CoRuO6 (−0.25≤x≤0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru5+→Ru4+ while hole-doped x≤0 compositions have a constant Ru5+ state. These observations support a proposed asymmetric doping model.

U2 - 10.1103/PhysRevB.72.014101

DO - 10.1103/PhysRevB.72.014101

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JO - Physical review B

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Orbital ordering and valence states in (La1+xCa1-x)CoRuO6 double perovskites

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Orbital ordering and valence states in (La₁+_xCa_1-x)CoRuO₆ double perovskites