Thermoelectric properties of ytterbium interstitial doped Sr0.7Ba0.3YbxNb2O6-δ ceramics

The thermoelectric properties of interstitial doped Sr0.7Ba0.3YbxNb2O6-δ ceramics were investigated in the temperature range from 323 K to 1073 K. The ytterbium interstitial doping contributes to increasing the power factor (PF) by improving the electrical conductivity. The PF values of Sr0.7Ba0.3Yb0.1Nb2O6-δ are comparable to those of the substitution doped sample with twice the doping content. This can be ascribed to the large electronic charge of the dopants relative to the occupied site in the interstitial case. The lattice thermal conductivity of Sr0.7Ba0.3YbxNb2O6-δshows a glass-like behavior due to lattice disorder. The disorder degree deepens as the doping content increases, resulting in plateau values of the lattice thermal conductivity at high temperatures in the Sr0.7Ba0.3Yb0.05Nb2O6-δ and Sr0.7Ba0.3Yb0.1Nb2O6-δ samples.