Effect of Ba/Y Molar Ratio on Superconducting Properties of BaTiO3-Doped YBa2Cu3 O 7−δ Films

Abstract

YBa2Cu3 O 7−δ (YBCO) films with BaTiO3 (BTO) nanostructures were prepared by using the precursor solutions with different cationic molar ratios of Y:Ba:Cu = 1.0:1.6–2.0:3.0 in the TFA-MOD process. These YBCO films were deposited on (00 l)-oriented LaAlO3 single-crystal substrates using a spin coater. The high superconducting critical current density (J C) (77 K, self-filed) of more than 10 MA/cm2 for the final BTO-doped YBCO film was obtained. Moreover, the effect of different Ba/Y molar ratios in the precursor solution on superconducting properties of BTO-doped YBCO films was investigated. Compared with the BTO-doped YBCO film deposited by using the precursor solutions with Ba/Y molar ratio of 2.0, an enhancement of J C in a magnetic field for the film from the solution with Ba/Y molar ratio of 1.9 was achieved. For Ba/Y molar ratios of 1.6 and 1.7, a reduction of J C in a magnetic field occurred. The J C enhancement may be mainly ascribed to the enhanced flux pinning by the Y2Cu2 O 5 nanostructures with the optimal number dispersing in YBCO matrix.