Research On Biazial Texture Of IBAD Buffer Template

Due to the large current capacity and high irreversible field,YBa₂Cu₃O_7-x（YBCO）coated conductors（CCs）have broad application prospects in transmission cable,magnet,motors,current limiters and so on.However,some challenges limit the using on commercial,such as biaxial texture with highly uniform,the uniformity along the tape,and the production cost.So,this dissertation focuses on the low cost fabrication biaxially textured buffer layers,and the details are as the following:By using solution deposition planarization（SDP）system,amorphous Y₂O₃ films were deposited on Hastelloy alloy（Hastelloy C276）substrate surface,which provides a good substrate for the growth of IBAD-MgO.Biaxially textured MgO film is grown on the Y₂O₃ surface by ion beam assisted deposition（IBAD）technology.Through the research and analysis various parameters of ion beam assisted deposition system,the optimal process of MgO film biaxial texture is obtain.We can get the MgO films with the out-of-plane texture yield full width at half maximun（FWHM）3?,and the in-plane texture yield of the FWHM about 6?.In all factors,the deposition rate of the films is the most important factor in the process of the biaxial texture obtained.The surface root mean square（RMS）of IBAD-MgO film is about 2nm,which provides a good conduction for growth of LMO layer.A 40m-long IBAD-MgO tapes has been prepared,the out-of-plane FWHM values about 3?,in-plane FWHM values about 6?.The result shows that the film has good texture and good uniformity.The situation to obtain biaxially textured IBAD-MgO thin film is strict.So we use the IBAD technology to explore new materials,and find that Na F and Na Cl can achieve the textured film by using IBAD technology,the out-of-plane and in-plane FWHM of Na F values 2.1?and 6.9?,and the out-of-plane and in-plane FWHM of Na Cl values 2.8?and 7.7?.Compared with the textured IBAD MgO process,which has the following advantages:First,the deposition rate of Na F and Na Cl thin film to form biaxial texture is 0.1-0.25nm/s and 0.05-0.3nm/s,but the deposition rate range of MgO is only0.175-0.2nm/s.Second,the surface of Y₂O₃ amorphous layer of the substrate roughness requirement is not so high.IBAD-Na F coatings on the 8 layers of the amorphous Y₂O₃layer（RMS=5.2nm）can form a better quality of biaxially textured,IBAD-Na Cl to obtain better biaxial texture need only coated with 4 layers of Y₂O₃ amorphous layer（RMS=9.7nm）substrate.The result showes that IBAD-Na F and IBAD-Na Cl can achieve with low difficulty.So it can improve the preparation efficiency of biaxial texture and reduce the cost.