Structural features of the superconducting single crystals of YBa{sub 2}Cu{sub 2.910}O{sub 6.58}

Tetragonal single crystals of YBa{sub 2}Cu{sub 2.910}O{sub 6.58} with {Tc} {approximately} 45-60 K are grown in ZrO{sub 2} crucibles. In the framework of the P4/mmm symmetry, a = 3.867(1), and c = 11.734(1) {angstrom}, the atomic structure of the crystals is refined. An analysis of the structural data led the authors to conclude about the random nature of the tetragonal symmetry of these superconducting samples. The local symmetry of the crystals is orthorhombic. The tetragonality is simulated by the merohedral microtwins. 15 refs., 3 figs., 3 tabs.