超声雾化方法中两步沉积对YBCO薄膜性能的影响

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

用自行研制的超声雾化装置在{110}<011>织构的Ag基带上直接沉积了YBCO涂层超导薄膜,结果发现一步沉积所得YBCO薄膜的表面有许多白色小颗粒,而且薄膜的织构和临界电流密度都较低,这是在900℃高温沉积过程中大量的Ag蒸发和扩散到YBCO膜层中所致．于是本文提出分高低温两步沉积的实验方案,即700℃先沉积15min,再升温到900℃沉积30min,通过SEM对薄膜表面和EDS能谱对薄膜的断面进行分析可知,两步沉积的YBCO薄膜中Ag的含量大大降低,而且薄膜的织构和临界电流密度得到明显改善和提高,最后通过两步沉积制备了15cm长、临界电流密度高于104A／cm2的YBCO超导薄膜．

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/cm^2 at 77K.