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Title: High-resolution EELS study of the vacancy-doped metal/insulator system, Nd{sub 1-x}TiO{sub 3}, x=0 to 0.33

High-resolution electron energy loss spectroscopy (EELS) spectra have been obtained for several members of the vacancy-doped metal/insulator perovskite system Nd{sub 1-x}TiO{sub 3} where NdTiO{sub 3} (x=0) is a Mott-Hubbard insulator and Nd{sub 2/3}TiO{sub 3} (x=0.33), a band insulator. The insulator to correlated-metal transitions occur at x{approx}0.20 and x{approx}0.10. Both O K- and Ti L{sub 2,3}-edge data were obtained on the title materials and the related d{sup 0} perovskites, CaTiO{sub 3}, SrTiO{sub 3} and BaTiO{sub 3}. The crystal structure of Nd{sub 0.70}TiO{sub 3} (x=0.30) was refined from powder neutron data in Cmmm which is taken as a model for the structure of Nd{sub 2/3}TiO{sub 3} (x=0.33) as well. The L-edge spectra for Nd{sub 1-x}TiO{sub 3} show systematic changes consistent with the valence state evolution from all Ti{sup 3+} (x=0.0) to all Ti{sup 4+} (x=0.33). Octahedral crystal fields of 1.5 and 2.0eV were inferred from the L-edge data for NdTiO{sub 3} and Nd{sub 2/3}TiO{sub 3} by comparison with calculated spectra from the literature. Broader L{sub 3} and L{sub 2} peak widths for Nd{sub 2/3}TiO{sub 3} than for the other d{sup 0} perovskites are attributed to the more complex crystal structure of this material which includes two Nd sites with partial occupation andmore » a more distorted Ti-O environment with low site symmetry. A markedly different O K-edge spectrum for Nd{sub 2/3}TiO{sub 3} is attributed to the involvement of Nd 5d levels.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [4] ;  [7]
  1. Brockhouse Institute for Materials Research, McMaster University, Hamilton (Canada) and Department of Chemistry, McMaster University, 1280 Main Street West (ABB-433), Hamilton, Ont., L8S 4M1 (Canada). E-mail: safasea@mcmaster.ca
  2. ICPET, NRC, Montreal Road, Ottawa (Canada)
  3. Department of Technical Science, National Centre for HREM, Delft University of Technology, Delft (Netherlands)
  4. Brockhouse Institute for Materials Research, McMaster University, Hamilton (Canada)
  5. (Netherlands)
  6. (Canada)
  7. (ABB-433), Hamilton, Ont., L8S 4M1 (Canada)
Publication Date:
OSTI Identifier:
20725866
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 178; Journal Issue: 4; Other Information: DOI: 10.1016/j.jssc.2004.12.027; PII: S0022-4596(04)00678-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BARIUM COMPOUNDS; CALCIUM COMPOUNDS; DOPED MATERIALS; ENERGY RESOLUTION; ENERGY-LOSS SPECTROSCOPY; NEODYMIUM COMPOUNDS; ORTHORHOMBIC LATTICES; OXIDES; PEROVSKITE; SPECTRA; STRONTIUM TITANATES; TITANATES; TITANIUM IONS; VACANCIES