Gd掺杂对无氟金属有机物沉积法制备Y1-xGdxBCO薄膜的应力调控  

Stress mechanism of Y_(1-x)Gd_xBCO thin film with Gd substitution prepared by F-free metal organic deposition method

作　　者：陈桢妮 刘胜利[2,3] 王海云[2] 程杰[2] 

机构地区：[1]南京邮电大学电子科学与工程学院,南京210003 [2]南京邮电大学理学院,先进功能陶瓷研究中心,南京210003 [3]南京大学(苏州)高新技术研究所,苏州215123

出　　处：《物理学报》2017年第15期206-212,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11405089);江苏省“六大人才高峰”人才项目(批准号:2014-XCL-015);苏州市科技局纳米技术专项基金(批准号:ZXG201444);南京邮电大学自然科学基金(批准号:NY215124,NY214105)资助的课题~~

摘　　要：为了揭示Gd掺杂对克服YBa_2Cu_3O_(7-δ)(YBCO)薄膜厚度效应的机制,采用无氟金属有机物沉积法在铝酸镧基底上沉积制备了一系列不同掺杂比例的Y_(1-x)Gd_xBCO薄膜,并且采用X射线衍射、扫描电子显微镜、Raman光谱仪分析薄膜的生长取向、微观形貌以及晶格振动特征,系统地研究了Gd掺杂对应力的调控机制.结果表明:随着Gd掺杂比例的增加,晶体的晶格常数变大,导致膜内的张应力增加,薄膜的c轴取向也随之升高;但是随着Gd含量的进一步增加,会使薄膜结构恶化,性能下降;当Gd:Y的掺杂比例为1:1时,薄膜的c轴晶粒取向最佳,可以有效克服厚度效应.Recently, the second-generation YBa2Cu3O7-δ （YBCO） high temperature superconducting materials have attracted much attention and become a hot research point. The YBCO coated conductors are widely used in transmission cables, motors, generators and magnetic energy storage systems due to their high critical current densities and high irreversible fields. To obtain high critical current, it is necessary to increase the thickness of YBCO film. However, as the thickness increases, the cracking of the film appears and the a-axis grains form, which causes the critical current density to decrease drastically, hence the critical current declines, i.e., the so called ＂thickness effect＂ appears. In order to overcome the ＂thickness effect＂, a great many of efforts have been devoted to it. It is realized gradually that the growth orientation of the c-axis can be controlled by the stress of film, which can be achieved through the substitution of Y by Gd and Sm each with a larger ionic radius. However, the systematical study of the evolution of the stress mechanism with the substitution ratio is still lacking due to the extreme complexity of the stress manipulation. Therefore, a series of YI-~ Gd~ BCO thin films with different substitution ratios is deposited on lanthanum aluminate substrates by the fluorine- free metal organic deposition method in order to reveal the evolution of the stress mechanism with Gd substitution. The growth orientations, microstructures and lattice vibration characteristics of the films are analyzed by X-ray diffraction, scanning electron microscopy and Raman spectroscopy. The results show that the lattice constant of the film increases and the orientation of the c-axis changes with the Gd substitution ratio for x increasing to a value less than 0.5, and the blue shift of the O（2）/O（3） mode of the Raman spectrum decreases with increasing x. For x -- 0.5, the blue shift of the 0（20）/（3） mode vanishes, indicating the free standing film with optimal c-axis orientation. However

关 键 词：YBA2CU3O7-Δ GD掺杂 RAMAN 

分 类 号：O484[理学—固体物理]