Diffusion von Yttrium und Scandium in stabilisierten Zirkoniumdioxid

Zr4位点上的Y3 （YSZ）、Sc3 （ScSZ）或Ca2 （CSZ）等低价阳离子在氧化锆中引入氧空位，扩大了立方相在浓度-温度空间的稳定范围，直至低温。这一特性使稳定氧化锆成为固体氧化物燃料电池技术应用的主要兴趣氧离子导体。在具有萤石结构的氧化物中，缓慢的阳离子扩散支配着扩散蠕变和电导率（阴离子）的长期老化。本课题研究的范围是钇在硅质硅中的扩散，钪和锆在硅质硅中的扩散。由于钇和钪都只有一种稳定同位素（89Y和45Sc），因此不可能使用稳定同位素技术，只能使用放射性示踪剂方法来研究钇或钪的扩散。所研究的材料应该是单晶和多晶立方YSZ（含8、10、18和24 mol % Y2O3）和多晶四边形YSZ（含3 mol % Y2O3）。在ScSZ的情况下，只有含有4到18 mol % Sc²O³的多晶材料是可用的。放射性同位素88Y、46Sc和95Zr应该被注入，然后在1000到1800℃的温度下扩散。利用经典的切片技术分析了放射性示踪剂的深度分布。

Lower valence cations like Y3 (YSZ), Sc3 (ScSZ) or Ca2 (CSZ) on Zr4 sites introduce oxygen vacancies in zirconia and enlarge the stability range of the cubic phase in the concentration-temperature space down to low temperatures. This feature makes stabilised zirconia an oxygen ion conductor of prime interest for technical applications in solid oxide fuel cells. In the oxides with fluorite structure the slow cation diffusion governs diffusion creep and long-term ageing of the electrical (anionic) conductivity. The scope of this project is the study of the diffusion of yttrium in YSZ and of scandium and zirconium in ScSZ. Since both yttrium and scandium have only one stable isotope (89Y and 45Sc), it is impossible to use stable isotope techniques: Only radiotracer methods can be used in order to study the diffusion of yttrium or scandium. The materials for investigation should be both single crystalline and polycrystalline cubic YSZ (containing 8, 10, 18 and 24 mol % Y2O3) and polycrystalline tetragonal YSZ (containing 3 mol % Y2O3). In the case of ScSZ, only polycrystalline material containing 4 to 18 mol % Sc²O³ is available. The radioisotopes 88Y, 46Sc and 95Zr should are implanted and then diffused at temperatures between 1000 and 1800°C. The depth distribution of the radiotracer is analysed using classical sectioning techniques.