Electric conductions in LaSrGaO and LaSrGaMgO

Dense La0.9Sr0.1Ga0.8Mg0.2O2.85 electrolyte for IT-SOFC's: Sintering study and electrochemical characterization

“…In addition, we can see that the˛g parameter in this study (see in Table 2) is smaller than one's obtained by Kurumada et al [55] for the composition La 0.9 Sr 0.1 Ga 0.9 Mg 0.1 O 2.9 in the temperature range between 200 • C and 380 • C: 0.93 ± 0.01. This difference probably comes from the content of substituted cations, higher for the La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 composition.…”

“…In other words, the capacitive component intergrains tends to change and would give place to a more "resistive" behaviour. Kurumada et al [55] explain this behaviour change by the dipole moment of the ions located at the grain boundaries As they are not packed up in a way as dense as those present in the grains, the dipole moment caused by the ionic displacement induced by the migration of the anions O 2− to the grain boundaries must be bigger than that induces by the migrations inside the grains. Thus, these bigger dipole moments must bring more large dielectric losses.…”

“…In the case of the ionic conductor, activation energies E M and E D are related to f tan ı and tan ı max according to the next equations [42,55,57,58]:…”

Electrical conduction and dielectric relaxation process in Ce0.8Y0.2O1.9 electrolyte system

“…The activation energy, E a for oxygen ionic conduction is the sum of E o and the migration energy E M [19]. The Nernst-Einstein formula for the ionic conductivity due to oxygen ion migration is represented by = 4e 2 ND/k B T, where 4e 2 is the square of the valence of an oxygen ion, and D ∝ exp(−E M /k B T) is the diffusion co-efficient of O 2− ions, N ∝ exp(−E O /k B T) is the density of the mobile free oxygen vacancies in thermal equilibrium because the assistance of vacancies is necessary in the O 2− diffusion, k B is the Boltzmann constant [8,27]. In the present oxide system, where the dielectric relaxation process do not show up in the loss factor ε , the activation energy is usually estimated by employing the approximation that the loss tangent is proportional to the loss factor, i.e., tan ı ∝ ε , then the maximum loss tangent has a form [8,9,11,[22][23][24][25][26][27][28][29].…”

Co-doping effects on crystal structure and electric conduction in ((YLa)Gd)ZrO

“…In the present oxide system, however, only the low-frequency peak shows up in the dielectric loss tangent, tand, as illustrated in Fig. 8a because the high frequencypeak at high temperatures requires the frequencies higher than the upper limit of the frequency range employed here [12,13] and the high-frequency peak of the weak intensity is fairly difficult to observe in the very high background of the loss tangent due to thermal disturbances. The realistic loss tangent values of the low frequency peak have been obtained by subtracting low-frequency contributions in the way similar to the previous treatments [11 -13,22,23,38] and are plotted in Fig.…”