Formation of epitaxial Tl sub(2)Ba sub(2)Ca sub(2)Cu sub(3)O sub(10) superconducting films by dc-magnetron sputtering and triple post-annealing method

• Published in: Chinese physics B 2014-07, Vol.23 (7), p.077401-1-077401-6
• Main Authors: Xie, Wei, Wang, Pei, Ji, Lu, Ge, De-Yong, Du, Jia-Nan, Gao, Xiao-Xin, Liu, Xin, Song, Feng-Bin, Hu, Lei, Zhang, Xu, He, Ming, Zhao, Xin-Jie
• Format: Article
• Language: English
• Subjects: Annealing; ANNEALING PROCESSES; Argon; COPPER OXIDE; CRYSTAL GROWTH; CURRENT DENSITY; Diffraction; Epitaxy; Evaporation; Magnetron sputtering; Oxygen content; Scanning electron microscopy; SPUTTERING
• ISSN: 1674-1056; 1741-4199
• DOI: 10.1088/1674-1056/23/7/077401

For obtaining pure phase TLBa sub(2)Ca sub(2)Cu sub(30)O sub(10) (Tl-2223) films with good superconducting properties, the growth technique is improved by dc magnetron sputtering and a triple post-annealing process. The triple post-annealing process comprises annealing twice in argon and once in oxygen at different temperatures. In the first low-temperature annealing phase in argon, Tl sub(2)Ba sub(2)CaCu sub(2)O sub(8) (Tl-2212) is obtained to effectively minimize evaporation in the next step. With the increase of temperature in the second annealing stage in argon, the previously prepared Tl-2212 inter-phase is converted into Tl-2223 phase. An additional annealing in oxygen is also adopted to improve the properties of Tl-2223 films, each containing an optimal oxygen content value. The results of X-ray diffraction (XRD) [straighttheta]-2[straighttheta] scans, [omega] scans and rotational [varphi] scans show that each of the Tl-2223 films has a high phase purity and an epitaxial structure. Smooth films are observed by scanning electron microscopy (SEM). The critical temperatures T sub(c) of the films are measured to be about 120 K and the critical current densities J sub(c) can reach 4.0 MA/cm super(2) at 77 K at self field.