掺碱土金属的双稀土铬酸盐(Pr_(0.5)Nd_(0.5))_(0.7)M_(0.3)CrO_(3-δ)(M=Sr,Ca)用于SOFC连接材料

Alkaline-earth-metal-doped Binary Rare Earth Chromites(Pr_(0.5)Nd_(0.5))_(0.7)M_(0.3)CrO_(3-δ)(M=Sr,Ca):Novel Interconnect Materials for SOFC

采用EDTA-柠檬酸法合成粉体,在1 400℃空气中烧结制备可用作固体氧化物燃料电池(SOFC)连接材料的两种掺碱土金属的双稀土铬酸盐(Pr_(0.5)Nd_(0.5))0.7Sr_(0.3)CrO_(3-δ)(PNSC)和(Pr_(0.5)Nd_(0.5))0.7Ca_(0.3)CrO_(3-δ)(PNCC)复合稀土,借助粒度分析仪、热膨胀仪、X射线衍射仪、扫描电镜、四端子测量仪等对连接材料的粉体粒度、致密度、断面微结构、烧结性能、导电性能以及热膨胀性能进行了分析。结果表明,PNCC具有更优的烧结性能,致密化烧结温度区间为900~1 030℃,而PNSC的烧结收缩发生在1 250℃以上。PNCC在1 400℃烧结4h达到97.2%的高致密度,而PNSC致密度只有76.5%,烧结性能与烧结过程中出现的CaCrO4或SrCrO4相有关。材料均遵从小极子导电机理,850℃下PNCC和PNSC的电导率分别达到50.4S·cm^(-1)和40.9S·cm^(-1)。PNCC的热膨胀系数为9.8×10-6 K-1,与YSZ电解质接近。因此,PNCC各项性能优于PNSC,是一种性能优良的固体氧化物燃料电池(SOFC)连接材料。

Using EDTA-pechini process to synthesize the primary powder,novel binary rare earth interconnect materials(Pr 0.5 Nd 0.5)0.7 Sr 0.3 CrO 3-δ(PNSC)and(Pr 0.5 Nd 0.5)0.7 Ca 0.3 CrO 3-δ(PNCC)for solid oxide fuel cells(SOFCs)were successfully prepared after sintering at 1 400℃in air.The particle size distribution,sintering shrinkage,structure,morphologies,electrical conductivity and thermal expansion were characterized by laser particulate size description analyzer,thermal expansion dilatometer,X-ray diffraction,scanning electron microscopy and standard DC four-probe technique.The results indicate that PNCC has higher sintering ability than PNSC.The sintering shrinkage of PNCC mostly happens at the temperature range of 900℃to 1 030℃,while the shrinkage of PNSC happens only above 1 250℃.The PNCC sample has a high relative density of 97.2%after sintered at 1 400℃for 4 h,however,the PNSC sample only has a lower relative density of 76.5%.The obvious different sintering ability may relate to the second phases of CaCrO 4 or SrCrO 4,which appears during the sintering process of PNCC or PNSC.The electrical conductivities of PNSC and PNCC can reach up to 50.4 S·cm^-1 and 40.9 S·cm^-1,respectively,at 850℃in air,and they both obey the theory of small polaron conduction.The thermal expansion coefficient(TEC)value of PNCC is 9.8×10-6 K^-1,very close to that of YSZ.These investigations have indicated that PNCC,better than PNSC,is a promising interconnect material for SOFCs.