SINGLE-CRYSTAL GROWTH AND PHASE-DIAGRAM STUDIES IN THE RBA(2)CU(3)O(7-X) SYSTEMS (R=Y AND RARE-EARTHS)

In this work the thermal conditions required for single crystal growth in the RBa(2)Cu(3)O(7-x) systems (R = Y or Rare Earths unless Ce and Tb) have been sistematically revised in order to improve the size of c rystals obtainable by the flux method. The 123 phases have been prepar ed and carefully examined by differential thermal analysis, thermograv imetry and x-ray powder diffraction. The RBa(2)Cu(3)O(7-x) -(BaCuO2+Cu O) pseudo-binary phase diagrams have been olso investigated. The tempe ratures of the peritectic decomposition of the 123 phases and the temp eratures of eutectic equilibria involving 123 phases and flux mixture have been determinated. The systems Nd, Sm and Eu-based systems show t he most wide range of temperature useful for crystal growth. In effect large single crystals of up to 20x15x0.8 mm(3) in volume have been ob tained for these system. The crystals have been characterized by XRD, oxygen content and electrical resistivity.