Power factor of La1−xSrxFeO3 and LaFe1−yNiyO3

The electrical conductivity (σ), Seebeck coefficient (S), and power factor (σS2) of perovskite-type LaFeO3, La1−xSrxFeO3 [0.1 ≤ x ≤ 0.4] and LaFe1−yNiyO3 [0.1 ≤ y ≤ 0.6] were investigated in the temperature range of 300–1100 K to explore their possibility as thermoelectric materials. The electrical conductivity of LaFeO3 showed semiconducting behavior, and its Seebeck coefficient changed from positive to negative around 650 K with increasing temperature. The electrical conductivity of LaFeO3 increased with the substitutions of Sr and Ni atoms, while its Seebeck coefficient decreased. The Seebeck coefficient of La1−xSrxFeO3 was positive, whereas that of LaFe1−yNiyO3 changed from positive to negative with increasing Ni content. The substitutions of Sr and Ni were effective in increasing the power factor of LaFeO3; 0.0053 × 10−4 Wm−1 K−2 for LaFeO3 (1050 K), 1.1 × 10−4 Wm−1 K−2 for La1−xSrxFeO3 (x = 0.1 at 1100 K) and 0.63 × 10−4 Wm−1 K−2 for LaFe1−yNiyO3 (y = 0.1 at 1100 K).