Enhancement of thermoelectric performance in rare earth-doped Sr 3Ti2O7 by symmetry restoration of TiO 6 octahedra

Yifeng Wang, Kyu Hyoung Lee, Hideki Hyuga, Hideki Kita, Hiromichi Ohta, Kunihito Koumoto

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

Aiming at the realization of the enhancement of thermoelectric performance through structural modification, the present work has clarified the significant effects of rare earth (RE=Gd, Sm, Nd, and La) doping at Sr-sites in Sr 3Ti 2O 7, both on the structural restoration of distorted TiO 6 octahedra and on the Seebeck coefficient, especially at high temperatures. The preferential substitution of RE 3+ at the nine-coordinate Sr-sites can facilitate the degeneration of the conduction band (Ti 3d-t 2g) orbital, owing to its special capability in restoring TiO 6 octahedra to a higher state of symmetry and thus enhance the density of states (DOS) effective mass of the carriers, which gives rise to a rather large increase in the Seebeck coefficient. The present findings have affirmed the effectiveness of structural restoration in enhancing the Seebeck coefficient by Sr-site-doping, which will help establish a useful solution for Ti-based thermoelectric oxides with inherently distorted TiO 6 octahedra to achieve high thermoelectric performance.

Original languageEnglish
Pages (from-to)76-82
Number of pages7
JournalJournal of Electroceramics
Volume24
Issue number2
DOIs
Publication statusPublished - 2010 Apr

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Mechanics of Materials
  • Materials Chemistry
  • Electrical and Electronic Engineering

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