【作者】 王显威；

【导师】 李中军；

【作者基本信息】 郑州大学 ， 应用化学， 2007， 硕士

【摘要】 钇稳定氧化锆（YSZ）具有氧离子电导率高及在工作环境下化学稳定性好等特点，在固体氧化物燃料电池（SOFC）中得到广泛应用。粒度分布窄的超细YSZ粉体有助于降低陶瓷的烧成温度，改善陶瓷的显微结构，从而提高陶瓷的电性能。本研究以氯化氧锆和氯化钇为原料，碳酸氢铵为沉淀剂，制备含锆、钇的复合沉淀，并经共沸蒸馏脱水和煅烧，得到了钇稳定氧化锆纳米粉体；将所得粉体球磨、成形和等静压处理后烧结制得钇稳定氧化锆陶瓷。运用TG/DSC、TEM、BET、XRD等实验手段对沉淀前驱体、共沸后粉体和煅烧所得YSZ粉体进行了相关表征，并运用SEM和交流阻抗谱等手段研究了陶瓷烧结体的显微结构和电性能。结果表明：1)实验所得前驱沉淀中锆和钇的物质量的比为5.49。2)共沸蒸馏不但可以有效地脱除沉淀中的水份，减轻颗粒间的团聚，而且还可以降低结晶转化温度。3)前驱粉体经800℃煅烧2h可得粒度分布较窄、粒径为20nm左右的球形立方相氧化锆粉体，粉体的比表面积为46.73m²/g。4)在1350℃烧结2h后，烧结体的气孔率急剧减少，烧结体的相对密度达到99.3％，晶粒大小为300nm左右；经1500℃烧结2h，烧结体的相对密度达到最大值99.9％。5)烧结体的晶粒电导率随着烧结温度的升高变化不大，晶界电导率随着烧结温度的升高而增加较大；烧结体的总电导率随烧结温度的升高先增加后降低，经1250℃、1300℃、1350℃、1500℃和1550℃烧结所得烧结体在1000℃时的电导率分别为0.157 S/cm、0.173S/cm、0.191 S/cm、0.213 S/cm和0.205S/cm。6)烧结体的晶粒和晶界电导活化能及总电导活化能的值在0.7—1.0ev的范围内变化。计算得到YSZ陶瓷（1350℃烧结）的晶界厚度为2.24nm，并导出真实晶界电导率s_gbt与表观晶界电导率s_gb的关系：s_gbt=0.0075s_gb。更多还原

【Abstract】 Yttria-stabilized zirconia （YSZ） is widely used as the solid electrolyte in solid oxide fuel cell （SOFC） because of its high oxygen conductivity and good chemical stability under the condition of the application. The density ceramic with good microstructure can be obtained at lower temperature using ultrafine powders with a narrow size distribution, and it may have the good electrical properties.The precipitate containing zirconium and yttrium was prepared using ZrOCl₂ and YCl₃ as raw materials and NH₄HCO₃ as the precipitant. YSZ nanopowder could be obtained by calcining the powder after dealing the precipitate with azeotropic distillation process, and the YSZ ceramics were prepared by sintering the green body obtained after ball milling and uniaxially pressing followed by the isostatically pressing. The precipitate, the powder after azeotropic distillation and the YSZ powder were characterized via TG/DSC、TEM、BET、XRD and some other experiment methods, and the microstructure and electrical property of the ceramic were studied using SEM, EIS and other methods. The results show:1) The molar ratio of Zr and Y in the precipitate is 5.49.2) The azeotropic distillation process can dehydrate effectively, alleviate the aggregation, and reduce the transformation temperature from amorphous zirconia to crystallized zirconia.3) The powders prepared by calcining the precursor after azeotropic distillation process at 800°C for 2 h are less-agglomerated cubic zirconia powders with a narrow size distribution, and the grain size and the specific area of the powders are～20nm and 46.73m²/g, respectively.4) After being sintered at 1350°C for 2 h, the fraction of porosity in the sintered body decreases rapidly, and ceramic obtained at 1350°C has the relative density of 99.3% and the grain size of about 300nm. The relative density of the ceramic sintered at 1500°C for 2h is 99.9%，which reaches up to the maximum.5) The grain boundary conductivity of the ceramic grows up with the rising of the temperature, while the grain conductivity almost has not changes with the altering of temperature. The total conductivities at 1000°C of the ceramics sintered at 1250°C, 1300°C, 1350°C, 1500°C and 1550°C are 0.157 S/cm, 0.173S/cm, 0.191 S/cm, 0.213 S/cm and 0.205S/cm, respectively.6) The activation energies of grain boundary conductivity, grain conductivity and total conductivity change in the rang from 0.7ev to 1.0ev. The relationship between the real grain boundary conductivity (s_gbt) and the apparent grain boundary conductivity (s_gb) can be expressed as s_gbt—0.0075s_gb, which is conducted from the calculated thickness of the grain boundary（2.24nm）.更多还原