Enhanced thermoelectric properties of WO3 by adding SnO2

Tungsten trioxide (WO3) doped with stannic oxide (SnO2) was prepared by a conventional mixed oxide processing route. The microstructure of the SnO2-added WO3 ceramics samples were investigated by X-ray diffraction and scanning electron microscopy. The grain size and porosity decreased with the increasing SnO2 content. The sign of the Seebeck coefficient for all samples was negative over the entire temperature range, i.e., n-type conduction. The addition of SnO2 to WO3 led to an increase in both the electrical conductivity and the absolute value of the Seebeck coefficient. This indicates that the power factor was significantly enhanced by adding SnO2 to WO3. The thermoelectric power factor was maximized to 7.77 μW m−1 K−2 at 1,023 K for the 10.0 mol% sample.