Crystal growth techniques for Tl-based cuprate superconductors

New techniques for the crystal growth of Tl-based cuprate superconductors h ave been developed. It is found that a gold crucible and closed atmosphere are crucial for their crystal growth by a so-called self-flux method for a long time. As an example, crystals of Tl2Ba2CuOx, which is most important a mong the Tl-based cuprate superconductors because of its wide T-c-change an d anomalous resistive critical fields, have been grown. Thus, mm-sized sing le crystals of Tl2Ba2CuOx in a high quality can be obtained. It should be n oted that the value of the resistivity ratio R(300 K)/R(T-c) (RRR) of one o f the as-grown crystals is 18.3. This high RRR value indicates that the new ly developed techniques are useful to obtain extremely high-quality single crystals of not only Tl2Ba2CuOx but also other Tl-based cuprate superconduc tors, (C) 2001 Elsevier Science B.V. All rights reserved.