Growth of Near-Free-Standing YBa2Cu3O7-Type Crystals Using a Self- Decanting Flux Method
Technical rept. no. 1, Oct 1990-Apr 1991,
NAVAL WEAPONS CENTER CHINA LAKE CA
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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 0.280.72 molar BaOCuO 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 1.85Ce0.15CuO4 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.
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