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

Jan-Willem G  Bos; J Paul Attfield; Ting Shan Chan; Ru Shi Liu; Ling Yun Jang

doi:10.1103/PhysRevB.72.014101

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

Jan-Willem G Bos, J Paul Attfield, Ting Shan Chan, Ru Shi Liu, Ling Yun Jang

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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 approximate to 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 (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.

Original language	English
Article number	014101
Number of pages	5
Journal	Physical Review B: Condensed Matter and Materials Physics
Volume	72
Issue number	1
DOIs	https://doi.org/10.1103/PhysRevB.72.014101
Publication status	Published - 1 Jul 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 approximate to 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 (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.",

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

AU - Bos, Jan-Willem G

AU - Attfield, J Paul

AU - Chan, Ting Shan

AU - Liu, Ru Shi

AU - Jang, Ling Yun

PY - 2005/7/1

Y1 - 2005/7/1

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 approximate to 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 (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 approximate to 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 (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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JF - Physical Review B: Condensed Matter and Materials Physics

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

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