Characterization of single crystals of high-tc superconductor la2-xsrxcu04

High-angle double-crystal X-ray diffractometry (HADOX) has been applied to examine the quality of La2-, SrxCu04 crystals grown by the travelling-solvent floating-zone method. The two-dimensional intensity distribution in reciprocal space is measured for 0014 and 400 with CoKaq radiation in a temperature range 60-260 K. The temperature dependence of the lattice constants is also measured. It is found that the crystal consists of grains or regions with different chemical compositions (Ax — 0.01), and that the corresponding crystallographic axes in different grains are parallel. A tetragonal-to-orthorhombic phase transition is reflected in changes in the crystal orientation, peak splittings and lattice constants as functions of temperature.