Doped With Transition Metal Oxides Of Ceo <sub> 2 </ Sub> Preparation And Properties Of Solid Electrolytes

In this paper, doped ceria based electrolyte were synthesized by low-temperature combustion synthesis, preparation conditions and properties of solid electrolyte were studied.Citric acid was used as reducing agent through compare in the experiment, and glycol was used for dispersant. The molar ratio of citric acid and nitrate was researched, we found that relative density and conductivity come to a head at 2.0. XRD show that cubic fluorite structure gained at 700℃calcined for 2h grown preferably. Dry-press method was used for shaping samples at 400MPa, and we found that sintering samples easily split under the condition of higher shaping pressure than 400MPa in a uniaxial die, which due to the after effect of elasticity.The experimental results showed nano powder of CGO was prepared by low-temperature combustion synthesis, which obviously decreased sintered temperature compared with 1500℃of normal powder. The relative density of CGO gained about 90% sintered at 1200℃. We found that doped cobalt oxide, ferric oxide and manganese oxide in Ce_0.8Gd_0.2O_2-δ (CGO)could enhance the relative density at some lower temperature range. Because of the exist of the viscous flow sintering, the rearrangement of grains were sped up, sintered process was quickened, and made sintered temperature lower than before. As a result of prolonging sintered hours, the relative density of doped 2%mol cobalt oxide in CGO obtained 95.2% at 1100℃sintered for 6h; The relative density of doped 2%mol ferric oxide in CGO gained 97.4% at 1200℃sintered for 6h, the densification rate approach academic density.Cobalt oxide and manganese oxide have similar effects on the conductivity of CGO:because Co³⁺ and Mn³⁺ ions with small radii dissolve into cubic fluorite structure, and bring the defects of Co'_Ce,Mn'_Ce, which tend to form defect complex with Vo. It is difficult to diffuse due to the defect complex. Finally the conductivity of doped samples were slightly decreased; Ferric oxide has scavenging effect on SiO₂ impurity, which increases the grain boundary conductivity, make the conductivity of doped CGO higher than CGO.