YBa2Cu3O7-δ Thin Film: Preparation by BaCl2/BaF2-MOD Method and Superconducting Property

Conventional trifluoroacetic acid metal organic chemical solution deposition (TFA-MOD) method for the preparation of YBa2Cu3O7- d (YBCO) superconducting layers follows the BaF2 growth mechanism. In this work, a novel chemical solution method based on BaCl2/BaF2 pathway for the growth of YBCO superconducting thin films was carried out. The effects of Cl addition on grain orientation, microstructure and superconductivity of YBCO thin films were investigated, and mechanism of the phase transition of YBCO thin films in the BaCl2 pathway was explored by thermochemical calculations of the growth reaction. The results show that the Cl addition inhibits alpha-axis grain orientation and promotes nucleation of c-axis grains. Onset transition temperature (Tc-onset) of the YBCO 2-layer film is about 89.6 K without significant change after Cl addition. But its critical current density (J(c)) is significantly increased to 2.07 MA/cm(2) (77 K, self-field). Meanwhile, the phase transition of the growth reaction process shows that Cl is preferentially combined with Ba to form BaCl2 as much as possible, effectively avoiding the formation of BaCO3. All results of this study indicate that Cl addition facilitates preparation of YBCO superconducting thick films, and provides a new idea for the preparation of YBCO by MOD method.

Automated summary

This study investigated the effects of Cl addition on the grain orientation, microstructure, and superconductivity of YBCO thin films grown by BaCl2/BaF2 pathway. It also explored the mechanism of the phase transition of YBCO thin films in this pathway through thermochemical calculations. The results showed that Cl addition inhibited the formation of alpha-axis grain orientation and promoted the nucleation of c-axis grains. The critical current density (Jc) of the YBCO film significantly increased to 2.07 MA/cm² (77 K, self-field) after Cl addition. Additionally, the phase transition process indicated that Cl preferentially combined with Ba to form BaCl2, effectively avoiding the formation of BaCO3. This study suggests that Cl addition facilitates the preparation of YBCO superconducting thick films and provides a new approach for YBCO preparation using the MOD method.