Crystal structures and superconductivity of superconducting phases in the Tl-Ba-Ca-Cu-O system

✍ Scribed by J.K. Liang; Y.L. Zhang; J.Q. Huang; S.S. Xie; G.C. Che; X.R. Chen; Y.M. Ni; D.N. Zhen; S.L. Jia

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 568 KB
• Volume: 156
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(88)90031-7

✦ Synopsis

We found a series of superconducting phases in the T1-Ba-Ca-Cu-O system and determined the crystal structures of these superconducting phases by means of the X-ray powder diffraction method. All of these superconducting phases belong to the tetragonal symmetry. They have the same lattice constant a and different lattice constant c. These superconducting phases can be divided into two types. The space group of type I is P4/mmm. The space group of type II is 14/mmm. The chemical formulae of type I and type II can be generalized as TIBa2Ca,_ ~Cu,O2~+2.5 (n= 2, 3, 4) and TI2Ba2Ca,,_ jCu,O2,+4 (n = 1, 2, 3 ), respectively. Tc increases as n increases. On the condition that n is the same, type II has a higher Tc than type I. The relations among the crystal structures of the superconducting phases are discussed. We propose a method which can deduce the crystal structure of the superconducting phase from the dr-value of the first diffraction line (00l) or lattice parameter c and which is confirmed by experimental data.