Relationship between crystallization process and superconducting properties of YBCO films by TFA–MOD method using starting solution with various compositions

Abstract

We have investigated the influence of partial pressure of water vapor [P(H2O)] in the crystallization process on the superconducting properties of YBa2Cu3O7−y (YBCO) films fabricated by a trifluoroacetate–metal organic deposition (TFA–MOD) method. The starting solution with different compositions of Y: Ba:Cu=1.0:2.0:3.0 and 1.0:1.5:2.0 were studied. The critical current density (Jc) values of YBCO films fabricated from Y:Ba:Cu=1.0:2.0:3.0 starting solution significantly increase (1.71→2.55MA/cm2) with increasing P(H2O) from 12.3 to 47.4kPa. In the YBCO films fabricated from Y:Ba:Cu=1.0:1.5:2.0 starting solution, high Jc values of over 2.5MA/cm2 were recognized in a wide range of P(H2O) (12.3–47.4kPa). One of the reason for Jc improvement is the suppression of coarsening of the secondary phases grains such as Y2Cu2O5 and CuO due to increase in growth rate of YBCO layer in the crystallization process. The Jc values of all YBCO films decreased as P(H2O) increased up to 70.1kPa. This degradation of Jc values may be caused by difference of crystal growth mechanism in high growth rate.