Effect of CeO2 on the thermoelectric properties of WO3-based ceramics

Improvement of thermoelectric properties of WO3 ceramics by ZnO addition

“…Previous study [24] implied that the densification of the WO 3 -based ceramics might be similar to the one that occurred in the SnO 2 -based polycrystalline systems, which was attributed to the increasing concentration of oxygen vacancies in the grain boundary region [30][31][32]. The densifying mechanism of the WO 3 -ZnO ceramics and the formation of oxygen vacancies could obey the following reactions:…”

“…On the basis of the XRD analysis, the rod-shaped structure is a grain of ZnWO 4 . Our previous researches suggested that the grain size of WO 3 -based ceramics remained almost constant with an average grain size about 10 m and that the open porosity was about 14% [20][21][22][23][24]. The grain size and the porosity of all samples in this research are given in Table 1.…”

“…Previous study [24] implied that the densification of the WO 3 -based ceramics was attributed to the increasing concentration of oxygen vacancies in the grain boundary region. The oxygen vacancies can be also introduced in the WO 3 ceramics by adding the ZnO to keep the charge neutrality when substituting the Zn 2+ ion for the W 6+ .…”

“…Therefore, it would be interesting to investigate the thermoelectric properties of WO 3 . We previously reported the thermoelectric properties of WO 3 doped with CeO 2 over the temperature range 323-673 K [24], and it was found that the addition of CeO 2 could densify the WO 3 ceramics to improve the thermoelectric characteristic. However, the electrical conductivity of the WO 3 -based ceramics is quite low and the higher temperature thermoelectric properties of WO 3 have not been reported, and thus the thermoelectric properties of WO 3 require further improvement and research.…”

Microstructures and electrical properties of copper oxide doped terbium oxide ceramics

“…Beyond x = 5.0 wt%, both are nearly stable. A recent study [33] revealed that the entire range of Tb formal oxidation states, from 4? to 3?, was observed depending on the -Tb-O-Tb-chain direction along which the vacancy was created, indicating that the variation in the distance of Tb-O and in the charge state of the Tb ion is associated with the oxygen vacancies.…”