Electrochemical study of the composite electrolyte based on samaria-doped ceria and containing yttria as a second phase (original) (raw)
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Ceria-based solid electrolytes
Solid State Ionics, 1996
Ceria-based solid electrolytes are reviewed in terms of electrical conductivity, diffusivity and transference number. The electrical conductivity and diffusion constants of various fluorite compounds are compared and those of ceria-based oxides are almost the highest among these fluorite oxides. The electrical conductivity of doped ceria is much dependent on the kind and the concentration of dopants. The reason for this behavior and a guideline to obtain more electrically conductive materials are discussed. The effect of sample preparation on the electrical conductivity is described in terms of the character of raw materials, impurities and the sintering condition. The factors to determine the transference number and the methods to increase the transference number at low oxygen pressures are also discussed.
Study on La and Y co-doped ceria-based electrolyte materials
Journal of alloys and …, 2007
Co-doped ceria electrolytes of Ce 0.8 La 0.2−x Y x O 1.9 (x = 0.02, 0.06, 0.10, 0.14, 0.20) fine powders were prepared with the sol-gel method. The results of X-ray diffraction and Raman spectroscopy showed that all powders crystallite calcined at 800 • C were single phase with cubic fluorite structure, the average crystallite sizes calculated by the Scherrer formula were between 27 and 34 nm, which was in good agreement with the results of TEM and particle size distribution measurements. The thermal expansion curves of Ce 0.8 La 0.2−x Y x O 1.9 were measured and the thermal expansion coefficients (TEC) between 100 and 800 • C were calculated. For the samples of Ce 0.8 La 0.2−x Y x O 1.9 , in the temperature range of 700-850 • C, when x = 0.06, 0.10 and 0.14, much higher ionic conductivity was observed than those of the singly doped ceria with same dopant concentration (20% trivalent rare earth) and when x = 0.06, maximal conductivity is obtained. It suggested that co-doping with appropriate ratio of lanthanum and yttrium can further improve the electrical performance of ceria-based electrolytes, and these co-doped samples may be the better electrolytes for intermediate-temperature solid oxide fuel cells. of oxygen vacancy, and therefore lower the activation energy of conduction and improve the ionic conductivity. And Kim found that the reduction of the lattice deviation of the doped ceria from the pure ceria would lead to the reduction of the lattice strain of the doped ceria, therefore, lead to the decrease of the activation energy of conduction and the increase of the ionic conductivity of the doped ceria. Up to now, some co-doped ceria-based electrolytes have been investigated, such as (
Role of salts on the electrical performance of ceria-based electrolytes: An overview
Frontiers in Materials
This work provides an overview on established achievements and debatable findings involving Ca, Gd or Sm-doped ceria-based electrolytes, using Li2CO3, LiNO3 and Na2CO3 as sintering aid or as second phase. The performance of these materials is discussed considering the characteristics of the oxides and of the salts or derived second(ary) phases (e.g., alkali metal oxides and hydroxides, eutectic mixtures), extensively surveyed to identify influential parameters with respect to processing and electrical performance (e.g., melting and boiling points, thermal decomposition, hydrolysis). The analysis of published data highlights the possible contribution of additional charge carriers to the total conductivity, besides oxide-ion vacancies. Claimed bulk and grain boundary conductivity enhancements are deeply discussed, as well as advantages and limitations of impedance spectroscopy as characterization tool. Irrespective of controversial reasons, reports on unusual improvements of grain bou...