Processing and conductivity behavior of La, Sm, Fe singly and doubly doped ceria: As electrolytes for IT-SOFCs

High Pressure X-ray Diffraction as a Tool for Designing Doped Ceria Thin Films Electrolytes

“…In Fig ure 2 the atomic arrangements of the F and the C phase are represented. From this perspective, it is possible to understand why in many doped ceria system two different values of activation energy can be recognized from the Arrhenius plot, wit the lower one at higher temperature [32][33][34][35]. This is quite a common feature in doped ceri systems, and it is ascribable to the occurrence of at least two different defect aggregate namely 1 •• ′ positively charged dimers and 1 •• 2 ′ neutral trimers [36].…”

“…This is quite a common feature in doped ceri systems, and it is ascribable to the occurrence of at least two different defect aggregate namely 1 •• ′ positively charged dimers and 1 •• 2 ′ neutral trimers [36]. In gen eral, a higher binding energy is calculated for dimers rather than for trimers [37]: as consequence, the latter, due to their lower configurational entropy, become progressivel less stable with increasing temperature, and their dissociation at a sufficiently high tem perature induces the release of oxygen vacancies which become able to migrate, thus re From this perspective, it is possible to understand why in many doped ceria systems two different values of activation energy can be recognized from the Arrhenius plot, with the lower one at higher temperature [32][33][34][35]. This is quite a common feature in doped ceria systems, and it is ascribable to the occurrence of at least two different defect aggregates, namely 1V •• O RE Ce positively charged dimers and 1V •• O 2RE Ce neutral trimers [36].…”

“…The crossover temperature results to be roughly the same for all the systems, and it was observed around 750 K [34]; in Figure 3, reproduced from [34], the trend of the activation energy below and above 750 K, as well as the preexponential factor A appearing in Equation ( 1 In spite of the large differences in ionic conductivity existing betw with different RE 3+ [34], the maximum in ( ) occurs within a na interval, namely at x (in Ce1−xRExO2−x/2) ranging between 0.10 and 0.2 the studied systems, such as for RE ≡ Gd [2], Sm [38], Lu [39], as well higher x, ionic conductivity significantly drops, and its absolute valu significant for any application; nevertheless, even heavily RE-doped interest in fundamental research, since they allow to correlate subtle transport properties [31,32,[40][41][42]. The substantial coincidence of the different systems suggests that the appearance in diffraction patterns o to defect clusters at largely different x values for different RE ions, do F phase has a different extent according to the RE identity; on the co gregates are present and stable even at very low RE concentration, bu ent spatial correlation, they can be identified by X-ray diffraction at di In addition to the numerous studies performed on singly-doped a large number of doubly-and multiply-doped systems has been in Gd/Y- [43], Gd/Sm- [44], La/Sm- [35], Sm/Nd- [45], Nd/Gd- [46], La/ [48]. A general lowering of activation energy [33] and an improveme In spite of the large differences in ionic conductivity existing between systems doped with different RE 3+ [34], the maximum in σ (σ max ) occurs within a narrow compositional interval, namely at x (in Ce 1−x RE x O 2−x/2 ) ranging between 0.10 and 0.25 for the majority of the studied systems, such as for RE ≡ Gd [2], Sm [38], Lu [39], as well as (Nd,Tm) [33].…”

“…In addition to the numerous studies performed on singly-doped ceria systems, also a large number of doubly-and multiply-doped systems has been investigated, such as Gd/Y- [43], Gd/Sm- [44], La/Sm- [35], Sm/Nd- [45], Nd/Gd- [46], La/Dy- [47], Gd/Sm/La [48]. A general lowering of activation energy [33] and an improvement of the ionic conductivity properties [43,49,50] with respect to singly-doped ceria is often observed.…”

The low infrared emissivity of Ce1-xYxO2-x/2 samples at high-temperature contributed by enhanced conductivity

“…Doping can improve the conductivity of metal oxides [9,10]. Therefore, in order to improve the conductivity of CeO 2 samples, doping is the most effective and convenient method.…”