Growth of near-free-standing YBa2Cu3O7-type crystals using a self-decanting flux method. Technical report No. 1, Oct 90-Apr 91

Large (Multi-millimeter-sized) near-free-standing platelets of YBa2Cu3OX have been obtained using a self-decanting flux method. The charge composition consists of 10.2 wt% YBa2Cu3O7 in a 0.28:0.72 molar BaO:CuO flux-mixture induced to decant by a thermal gradient. After oxygen annealing, crystals display sharp Tc values near 92 K. Crystals of ten of the RBa2Cu3Ox congeners, R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, And Yb, were also grown using the method described. Preliminary experiments were successful in adapting the procedure to the Nd (1.85)Ce(0.15)CuO4 system and yielded small, superconducting (Tc > 20 K) platelets after Ar-annealing. For the YBa2Cu3Ox system, an oxygen annealing study was conducted in order to determine the best conditions for the reliable production of crystals with optimized superconducting properties.