Preparation of high performance YGdBCO films by low fluorine TFA-MOD process

Abstract

YBCO films doped with different contents of gadolinium (Gd) were prepared by the low-fluorine (low-F) trifluoroacetate metal-organic deposition (MOD) method. The effects of flow rate and holding time of the firing (crystallization) stage on the superconducting properties of YxGd1–xBa2Cu3O7–δ (YGdBCO) films were investigated. The phase formation and texture were characterized by the X-ray diffraction (XRD), which indicate that severe degradation of the microstructure will be induced with the inappropriate flow rate. The surface morphology and element distribution were investigated by the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that increasing the holding time of the firing stage is effective for the further decomposition of residual impurity phase on the surface. The mechanisms of the phase and surface evolution are also discussed. Finally, a high critical current density (Jc) value of 5.4 MA/cm2 was achieved in the Y0.9Gd0.1BCO film fabricated by the cooperative control of the flow rate and holding time of the firing stage, which are contributed to the formation of excellent texture, homogeneous microstructure and dense surface of the YGdBCO films.