Single crystal growth and phase diagram studies in the RBa 2Cu 3O 7−x systems (R = Y and rare earths)

Abstract

In this work the thermal conditions required for single crystal growth in the RBa 2Cu 3O 7-x systems (R = Y or Rare Earths unless Ce and Tb) have been sistematically revised in order to improve the size of crystals obtainable by the flux method. The 123 phases have been prepared and carefully examined by differential thermal analysis, thermogravimetry and x-ray powder diffraction. The RBa 2Cu 3O 7−x(BaCuO 2+CuO) pseudo-binary phase diagrams have been olso investigated. The temperatures of the peritectic decomposition of the 123 phases and the temperatures of eutectic equilibria involving 123 phases and flux mixture have been determinated. The systems Nd, Sm and Eu-based systems show the 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 obtained for these system. The crystals have been characterized by XRD, oxygen content and electrical resistivity.