TFA-MOD derived YBa 2 Cu 3 O 7-x thick films assisted by a high magnetic field Wang H, Wang Q L, Huang H Li B L, Ma Y W, Yan L G Applied Superconductivity Technology Research Division, IEE CAS Institute of Electrical Engineering CAS

Outline  Difficulties in fabrication of thick YBCO film for coated conductors  Offer a new method  Theoretical analyses for feasibility Institute of Electrical Engineering CAS

Biaxially textured YBCO coated conductor from epitaxial growth Metallic substrate Ceramic buffer layers YBCO film Institute of Electrical Engineering CAS In situ, eg. PLD, CVD Ex situ, eg. TFA-MOD Two kind techniques: Present level Applicat ion level JcJc tsts 1 MA/cm 2 1m1m ≥5  m

Thickness limitation of epitaxial growth method and application of HMF Institute of Electrical Engineering CAS Non-oriented YBCO grains ∝ tsts c oriented YBCO grains Textured buffer layers J tsts t lim JcJc J eng Epitaxial growth techniques (PLD, LPE, TFA-MOD, etc): t lim ≤1.5 m H ex tsts

High magnetic field assisted TFA- MOD method for thick YBCO film Institute of Electrical Engineering CAS Metal trifluoroacetate solution Film coating Low temperature roasting High temperature roasting with HMF 3 useful effects of HMF in theory Magnetic orientation Magnetically preferred nucleation Magnetic interaction

Magnetic orientation of non-oriented YBCO nuclei during chemical reaction Institute of Electrical Engineering CAS 7nm liquid layer at the growth interface (Solovyov, 2000) Growthdirection Fr. texturedbuffer layer YBCO: # Orthorhombic system # △ χ c-a ＝ 1.2×10 -9 m 3 /kg (330 ℃ ) # 1030 ℃, 7T, solidification, ok (Lee et al, 1992) High T roasting: 850 ℃, 30min

Magnetically preferred nucleation of YBCO during chemical reaction Institute of Electrical Engineering CAS YBCO: Magnetic refining of YBCO grains during MOCVD on MgO substrate (Ma Yanwei et al, 2000 ) 0T0T 4T 2T 8T

Magnetic interactions between c-axis oriented YBCO grains Institute of Electrical Engineering CAS H ex c c 1 2 Two possible effects: Maintain c-axis texture in thick YBCO film Densify the thick YBCO film

Conclusions: When HMF ⊥ Textured substrate  The field is of benefit to maintain high quality c-axis texture so as to be good for biaxial texture in thick YBCO film.  HMF assisted TFA-MOD method is a promising new technique to obtain practical YBCO coated conductors. Institute of Electrical Engineering CAS The experiments are undergoing!

WANG HUI ： (O) (Fax) Institute of Electrical Engineering CAS