Improvement of YBCO Film Properties by Two-step Deposition Using Spray Pyrolysis Method

The YBCO films were directly deposited on the {110} 011 textured Ag substrates by an ultrasonic spray pyrolysis method using the modified device. The YBCO film made by one-step deposition at 900℃on textured Ag substrate has a weak in-plane texture and low Jc value. The observed white points in this film consist of high content of Ag on the surface of this film, which are due to the vaporization and diffusion of Ag atoms at high deposition temperatures. While the performance of YBCO films can be significantly enhanced by using two-step deposition route, firstly pre-depositing the precursor film at 700℃then carrying out the second step depositing at 900℃.The results show that the two-step deposition can effectively prevent Ag atoms from vaporizing and diffusing into YBCO films and improve the surface roughness, texture and superconducting properties of YBCO films. The YBCO film being 15cm long, coated on {110} 011 textured Ag tape by this two-step deposition method exhibits a transport Jc value of more than 104A/cm2 at 77K.