N.N. Kolesnikov, M.P. Kulakov, V.N.
Molchanov, I.F. Schegolev, R.P. Schibaeva, V.I., Simonov, R.A. Tamazyan,
Comparative study of Tl-2201 single crystals with Tc=30
and 110 K by means of X-ray structural analysis and NMR.
The crystal structure of a tetragonal single crystal of Tl-2201 with
Tc=30 K has been determined by the X-ray diffraction
technique (a = 3.8717(3), c = 23.224(3) Angstrom, space
group I4/mmm, Z = 2). The chemical composition is found to be Tl1.90(1)Cu0.10(1)Ba2CuO6.18(4).
Displacements of Tl and O3 atoms from their symmetric sites have been observed.
Structural parameters of Tl-2201 cuprates with various Tc
have been compared. The superconducting transition temperature is shown
to correlate most strongly with the parameter c, with the length
of the bond between Cu and apical oxygen as well as with the distance between
Ba2+ and the cuprate plane.