On Nb site: A paramagnetic Jahn-Teller center in vacuum-reduced single crystals

G. Corradi, I. Zaritskii

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

An axial EPR signal observed in vacuum annealed (Formula presented) single crystals doped with 8 mol % Mg and 0.05 mol % Ti has been attributed to (Formula presented) on Nb site. The (Formula presented) tensor components (Formula presented) and (Formula presented) for (Formula presented) and (Formula presented) for (Formula presented), resulting in outstandingly low values of the orbital reduction factor (from (Formula presented) to 0.13), can be explained by a dynamic pseudo-Jahn-Teller effect. The vibronic coupling of the center is much stronger than that reported for other (Formula presented) centers with similar trigonally distorted octahedral coordination in (Formula presented) like the (Formula presented) on Li site and trapped (Formula presented) polarons on both cation sites. Stronger coupling for ions on or near the Nb site is understood as a result of smaller trigonal splitting of the ground state due to the more central position of the Nb site in the oxygen octahedron. Electron transfer from the observed (Formula presented) center to lattice niobiums, resulting in (Formula presented) trapped polarons, has been stimulated by illumination in the near UV region. The average energy difference of the involved (Formula presented) and (Formula presented) donor levels has been estimated to be (Formula presented) depending also on the distance of compensating (Formula presented) ions on nearby Li sites.

Original languageEnglish
Pages (from-to)8329-8337
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume58
Issue number13
DOIs
Publication statusPublished - Jan 1 1998

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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