Thermoelectric power of Gd-doped CeO2 (Gd0.1Ce0.9O(2−δ) (GDC10)): Measurements on porous samples

Thermoelectric behavior of a mixed ionic electronic conductor, Ce1−xGdxO2−x/2−δ

“…The as-measured oxygen nonstoichiometry has turned out to be sufficiently precisely fitted to eqn (8), rather than eqn (7), in association with eqn (2), as delineated by solid lines in Fig. 2a.…”

“…Still, most of them are on the system of yttria-stabilized zirconia [see, e.g., ref . 5] and only two on the system of present interest GDC, 6,7 reporting that the thermopower changes its sign as the majority carriers change from oxide ions to electrons with decreasing oxygen activity 6 and that it is dependent on the porosity of the specimen. 7 This work aims: (i) to document the thermopower of GDC in two apparently different thermodynamic conditions that are present when the oxygen nonstoichiometry distribution is uniform (rd = 0) and constant (rd a 0), be it Soret equilibrium or gas-solid oxygen exchange equilibrium; (ii) to develop a thermodynamic theory on the thermoelectricity of a mixed oxide ionic electronic conductor; (iii) to compare it with the already existing theory for mixed electron-hole conductors; (iv) to estimate the heats of transport, that is, the quantity coupling the heat flow and charge flow by oxide ions and electrons; and finally (v) to present a somewhat provoking result on the so-called kinetic term of electrons or small polarons in GDC.…”

Determination of Oxygen Transport Properties from Flux and Driving Force Measurements

“…Thermovoltages have also been dismissed as an error term. While heat from the oxidation reaction will change the temperature at the probe tip, the enthalpy of oxidation should only be weakly temperature dependent and as the thermopower of the CG10 probe increases with temperature, 34 the thermovoltage would not experience the decrease of r s with temperature seen in Fig. 11b.…”

(Invited) Transport Properties of Mixed Ionic Electronic Conductors under Thermodynamically Equilibrated Conditions: Measurements on Porous Bodies

“…Thermoelectric Power: Figure 2(a) shows the results of measurements of thermoelectric power on a dense GDC sample [1]. The average sample temperature was ~500 o C. A ΔT of 9 degrees and 18 degrees was maintained across the sample in two consecutive tests using an electrical heater.…”

“…In this manuscript, we report measurements of four different properties using porous samples of various materials (and samples with porous surface layers) and compare with results obtained on dense samples. The four properties studied were: (a) Thermoelectric power of Gd Thermoelectric Power: Figure 2(a) shows the results of measurements of thermoelectric power on a dense GDC sample [1]. The average sample temperature was ~500 o C. A ΔT of 9 degrees and 18 degrees was maintained across the sample in two consecutive tests using an electrical heater.…”