Thermoelectric properties of Sr1-xLaxNb2O6-δ (0 < x ≤ 0.4) ceramics sintered under strongly-reducing conditions

A series of oxide ceramics with the general formula of Sr1-xLaxNb2O6-delta (x = 0.1, 0.2, 0.3, 0.4) was synthesized and the characterization was study in detailed. The XPS results reveal that the hetemvalent substitution of La3+ for Sr2+ leads to the Nb4+ dominated chemical state in this series of oxides, and a mass of oxygen vacancy defects exist in the oxides after annealed in strong reduction atmospheres. Due to increased phonon scattering by lattice distortion and heavier La atoms, all of the samples achieve lower thermal conductivity. The electrical resistivity and the magnitudes of Seebeck coefficient monotonically decrease with the increase of the content of lanthanum. Overall, the sample of Sr0.6La0.4Nb2O6 reaches the maximum ZT of similar to 0.13 at 1073 K.

Automated summary

A series of oxide ceramics with the general formula of Sr1-xLaxNb2O6-delta were synthesized and studied. The substitution of La3+ for Sr2+ increases the Nb4+ chemical state and introduces oxygen vacancy defects. Due to lattice distortion and heavier La atoms, the thermal conductivity, electrical resistivity, and Seebeck coefficient decrease. Among the samples, Sr0.6La0.4Nb2O6 reaches the highest ZT value of approximately 0.13 at 1073 K.