Transport and thermoelectric properties of n-type Ruddlesden–Popper phase (Sr1−xGdx)3(Ti1−yTay)2O7 oxides
Year: 2012
Type: article
Abstract: The transport and thermoelectric properties of (Sr1−x Gd x )3(Ti1−y Ta y )2O7(x = 0.05, y = 0.05–0.15; x = 0.1, y = 0.05–0.1) compounds with Ruddlesden–Popper (RP) phase, prepared by a conventional solid-state reaction method plus spark plasma sintering (SPS), were investigated in the temperature range from 300 to 1000 K. The results indicate that the electrical resistivity ρ for all compounds increases with temperature, and has a relation ρ ∝ T M (i.e. the mobility μ ∝ T −M ) with M = 1.58–1.92 at T ≳ 650 K, indicating that the phonon scattering is predominant. Basically, the absolute value of the Seebeck coefficient |S| increases almost linearly with temperature above ∼400 K, showing degenerated semiconducting behaviour. Moreover, both ρ and |S| decrease with the increase in both Ta and Gd content, which can be attributed to an increase in the carrier concentration. The lattice thermal conductivity κ L of the compounds decreases monotonically with an increase in both Ta and Gd content due to mass-defect phonon scattering, and the lowest κ L(κ L = 3.3 W K−1m−1 at room temperature and 2.0 W K−1 m−1 at 1000 K) is achieved in (Sr0.9Gd0.1)3(Ti0.9Ta0.1)2O7. Among all the compounds investigated here, the largest dimensionless figure of merit ZT = 0.08 (at 1000 K) is obtained in the compound (Sr0.9Gd0.1)3(Ti0.95Ta0.05)2O7.
Institutions: Chinese Academy of Sciences, Institute of Solid State Physics
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1587665422