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 e quilibrated (held in the furnace for at least 10 min) MgO single cryst als into the melt and analyzing the melt stuck to the MgO by ICP; b) d ipping a relatively cool not thermally equilibrated Al2O3 polycrystall ine rod into the melt (i.e. effective quenching) and analyzing the mel t stuck to the rod by ICP. The measurements have been made in the temp erature range from approximately 950 degrees C up to about 1300 degree s C. Following thermodynamic calculations, expressions for the liquidu s lines are derived and the enthalpy of dissolution for the various RE 123 and RE211 are calculated to be nearly the same for the same melt c omposition. Nevertheless a small increase of the enthalpy of dissoluti on with increasing peritetic temperature could be detected.