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Title: Orbital ordering and valence states in (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites

Abstract

(La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO{sub 6} 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{approx_equal}425 K, which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co{sup 2+} t{sub 2g} holes. Ru valence states of doped (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} (-0.25{<=}x{<=}0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru{sup 5+}{yields}Ru{sup 4+} while hole-doped x{<=}0 compositions have a constant Ru{sup 5+} state. These observations support a proposed asymmetric doping model.

Authors:
; ; ; ;  [1];  [2];  [3];  [3]
  1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (United Kingdom)
  2. (United Kingdom)
  3. (China)
Publication Date:
OSTI Identifier:
20719097
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 72; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevB.72.014101; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION SPECTROSCOPY; CALCIUM COMPOUNDS; COBALT COMPOUNDS; COBALT IONS; DOPED MATERIALS; ELECTRONS; HOLES; LANTHANUM COMPOUNDS; NEUTRON DIFFRACTION; PEROVSKITES; RUTHENIUM IONS; RUTHENIUM OXIDES; SUPPORTS; THERMAL EXPANSION; VALENCE; X-RAY SPECTROSCOPY

Citation Formats

Bos, Jan-Willem G., Attfield, J. Paul, Chan, T.-S., Liu, R.-S., Jang, L.-Y., Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, Department of Chemistry and Center for Nano Storage Research, National Taiwan University, Taipei 106, and National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan. Orbital ordering and valence states in (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites. United States: N. p., 2005. Web. doi:10.1103/PhysRevB.72.014101.
Bos, Jan-Willem G., Attfield, J. Paul, Chan, T.-S., Liu, R.-S., Jang, L.-Y., Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, Department of Chemistry and Center for Nano Storage Research, National Taiwan University, Taipei 106, & National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan. Orbital ordering and valence states in (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites. United States. doi:10.1103/PhysRevB.72.014101.
Bos, Jan-Willem G., Attfield, J. Paul, Chan, T.-S., Liu, R.-S., Jang, L.-Y., Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, Department of Chemistry and Center for Nano Storage Research, National Taiwan University, Taipei 106, and National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan. Fri . "Orbital ordering and valence states in (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites". United States. doi:10.1103/PhysRevB.72.014101.
@article{osti_20719097,
title = {Orbital ordering and valence states in (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites},
author = {Bos, Jan-Willem G. and Attfield, J. Paul and Chan, T.-S. and Liu, R.-S. and Jang, L.-Y. and Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ and Department of Chemistry and Center for Nano Storage Research, National Taiwan University, Taipei 106 and National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan},
abstractNote = {(La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO{sub 6} 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{approx_equal}425 K, which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co{sup 2+} t{sub 2g} holes. Ru valence states of doped (La{sub 1+x}Ca{sub 1-x})CoRuO{sub 6} (-0.25{<=}x{<=}0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru{sup 5+}{yields}Ru{sup 4+} while hole-doped x{<=}0 compositions have a constant Ru{sup 5+} state. These observations support a proposed asymmetric doping model.},
doi = {10.1103/PhysRevB.72.014101},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 1,
volume = 72,
place = {United States},
year = {2005},
month = {7}
}