High-resolution EELS study of the vacancy-doped metal/insulator system, Nd{sub 1-x}TiO{sub 3}, x=0 to 0.33
- 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)
- ICPET, NRC, Montreal Road, Ottawa (Canada)
- Department of Technical Science, National Centre for HREM, Delft University of Technology, Delft (Netherlands)
- Brockhouse Institute for Materials Research, McMaster University, Hamilton (Canada)
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 and 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.
- OSTI ID:
- 20725866
- Journal Information:
- Journal of Solid State Chemistry, Vol. 178, 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); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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