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用透射电镜、扫描电镜、俄歇电子谱仪和金相偏振光显微术观测了YBCO超导体中第二相的形态、结构、成分和分布。绝大多数123YBCO晶粒均为孪晶层状结构。孪晶片宽度为5～100nm。孪晶边界通常是清洁的,无第二相杂质分布。123晶粒之间有时可以发现少量第二相畴(畴区尺寸约为1μm)。123晶粒内有尺寸较小的(约几十nm)非超导相微畴存在。本研究所用样品中大多数晶粒边界(～70%)没有第二相存在。约30%的晶界处常可发现第二相粒子及非晶物质等,并使晶界成为多层形态。俄歇谱数据表明,这样的边界是富钡和碳,贫铜和钇。结构分析表明,第二相粒子团包括碳酸钡、氧化铜或其他碳化物等。文章对第二相分布对材料超导电性的影响也进行了讨论。
The morphology, composition, composition and distribution of the second phase in the YBCO superconductor were observed by transmission electron microscopy, scanning electron microscopy, Auger electron microscopy and metallographic polarization microscopy. The vast majority of 123YBCO grains are twin layered structures. Twins width of 5 ~ 100nm. The twin boundaries are usually clean, with no secondary phase impurity distribution. A small number of second phase domains can sometimes be found between grains (domain size is about 1 μm). There are small (about tens of nm) non-superconducting phase micro-domains present in the 123 grains. Most of the grain boundaries (~ 70%) in the samples used in this study did not have a second phase present. About 30% of the grain boundaries often found in the second phase particles and amorphous material, and so that the grain boundary into a multi-layer morphology. Auger spectroscopy data show that such boundaries are rich in barium and carbon, poor in copper and yttrium. Structural analysis shows that the second phase particles include barium carbonate, copper oxide or other carbides and the like. The influence of the second phase distribution on the superconductivity of the material is also discussed.