采用低氟溶胶-凝胶法在725℃煅烧温度下制备YBCO超导薄膜的研究

Preparation of YBa2Cu3O7-x Films at the Firing Temperature of 725 °C by a Low-Fluorine Sol-Gel Method

摘要:

采用低氟溶胶-凝胶法在LaAlO₃(100)基板上制备了YBa₂Cu₃O_7-x (YBCO)薄膜,研究了725℃的煅烧过程中氧含量对最终所得到YBCO薄膜的临界电流密度J_c的影响。研究发现,煅烧过程中氧气含量在100-1700 ppm范围内时,所获得的YBCO薄膜均具有良好的双轴织构特征。然而,当氧气含量较小时,所获得的YBCO薄膜致密性差,J_c较低。随着氧气含量的增大,YBCO薄膜表面逐渐变得致密。当氧气含量增加到300ppm时,YBCO薄膜表面较致密,J_c值达到4.3MA/cm₂。继续增大氧含量,薄膜表面出现富铜的第二相颗粒并逐渐增多,导致薄膜J_c降低。

Abstract:

In this paper, the YBa₂Cu₃O_7-x (YBCO) films were prepared on LaAlO₃ (100) substrate using a low-fluorine sol-gel method. The effect of the oxygen content during firing YBCO films at 725 °C on the critical current density (J_c) of the resulting YBCO films were investigated. It is found that all the YBCO films fired in the oxygen content scale of 100~1700 ppm exhibit good biaxial-texture characteristics. However, the YBCO film is less dense when the oxygen content is low and thus the critical current density (J_c) of the film is inferior. The film surface becomes denser with increasing the oxygen content during the firing process, and J_c of the film reaches 4.3 MA/cm₂ when the oxygen content is elevated to 300 ppm. Furthermore, many copper-rich second phases appear on the films surfaces and become more gradually with the further elevating the oxygen content, resulting in the decline of J_c.