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.
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