Size effect study by bulk crystals: Optical and DC dielectric response of oxygen vacant BaTiO3

Y. Watanabe, M. Okano, G. A. Thomas, S. W. Cheong

Research output: Contribution to journalConference articlepeer-review

11 Scopus citations


We have studied the wide-range dielectric spectra of BaTiO 3-δ single crystals and traced the evolution of the electronic structure of BaTiO3 with a very low oxygen vacancy concentration δ An extremely small δ can destroy the band edge and the Urbachian temperature dependence, and a so-called mid-infrared (ir) absorption band which shows no hump like absorption spectrum. At a slightly larger δ, an absorption spectrum has a hump like shape and exhibits temperature dependence distinctly different below and above Curie temperature. At this δ, the permittivity is enhanced by five times and exhibits a large frequency dispersion. The observations suggest a possible coupling of oxygen vacancy with a mesoscopic spontaneous polarization and elucidate the origin of mid-ir absorption generally observed in doped oxides. The implications for relaxor and the size effect are discussed.

Original languageEnglish (US)
Pages (from-to)37-42
Number of pages6
Issue number1
StatePublished - 2001
Externally publishedYes
Event3rd Asian Meeting on Ferroelectrics, AMF-3 - Hong Kong, China
Duration: Dec 12 2002Dec 15 2002

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


  • ferroelectric
  • infrared
  • oxygen vacancy
  • relaxor
  • size effect


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