SOLUBILITY OF RE ELEMENTS INTO BA-CU-O MELTS AND THE ENTHALPY OF DISSOLUTION

The liquidus compositions of Y, Sm, Gd, Dy and Yb for a melt with a Ba to Cu ratio of 3 to 5 has been investigated by a) dipping thermally equilibrated (held in the furnace for at least 10 min) MgO single crystals into the melt and analyzing the melt stuck to the MgO by ICP; b) dipping a relatively cool not thermally equilibrated Al2O3 polycrystalline rod into the melt (i.e. effective quenching) and analyzing the melt stuck to the rod by ICP. The measurements have been made in the temperature range from approximately 950 degrees C up to about 1300 degrees C. Following thermodynamic calculations, expressions for the liquidus lines are derived and the enthalpy of dissolution for the various RE123 and RE211 are calculated to be nearly the same for the same melt composition. Nevertheless a small increase of the enthalpy of dissolution with increasing peritetic temperature could be detected.