N.N. Kolesnikov, V.E. Korotkov, M.P. Kulakov, G.A. Logvenov, V.N. Molchanov, L.A. Muradyan, V.I. Simonov, R.A. Tamazyan, R.P. Shibaeva, I.F. Shchegolev.
Structure of superconducting TlBa₂(Ca_0.87Tl_0.13)Cu₂O₇ single crystals with T_c=80K.

  Abstract:
 The crystal structure of single crystals of the 1212 phase in the system TL-Ba-Ca-Cu-O has been determined: a=3,8472(5), c=12,721(3) Angstrom, sp.gr. P4/mmm. The chemical formula of this phase has been refined: TlBa₂(Ca_0.87Tl_0.13)Cu₂O₇,  T_c=80 K, Meissner effect is 75-80%.