关于YBCO薄膜过热现象的研究

Study on the superheating phenomenon of YBCO thin film

在用YBa_2Cu_3O_z(YBCO)种膜液相外延生长Nd^(1+)xBa_)2-x_CuO_z(NdBCO)厚膜的过程中,YBCO晶体在高于熔点的温度下保持不熔化并且起到了外延种子的作用.采用高温金相显微镜,我们实时观察YBCO薄膜的熔化过程,发现了超导氧化物薄膜的过热现象,并且结合XRD极图的分析和Ba-Cu-O熔体的不润湿性现象合理解释了YBCO形成过热的机制.另外,通过对具有不同微观结构的YBCO薄膜熔化行为的横向比较,研究YBCO薄膜品质对于其过热度的影响,并用半共格界面能理论很好地解释了AFM和XRD分析及实时观察熔化过程的实验结果.

By using high temperature optical microscopy （HTOM）, the superheating phenomenon in YBa2Cu3Oz （Y123） oxide thin film was found by in-situ observation of its melting process. The origin of superheating is discussed in combination with the analysis of XRD pole figure and the unwettability of Ba-Cu-O melts. Besides, the relationship between the microstructure of YBCO thin film and its superheating degree was investigated. The film with lower fraction of interface defects is believed to have higher superheating degree. The results deduced from semi-coherent interface energy theory are in good agreement with the experimental results of HTOM, AFM and XRD.