INTERACTIONS BETWEEN YBA2CU3O7-X AND K2CO3

The interactions between YBa2Cu3O7-x and K2CO3 have been studied using thermochemical methods, isothermal annealing of diffusion pairs, opti cal microscopy, X-ray diffraction, and microprobe analyses. The experi ments have shown existence of solubility of YBa2Cu3O7-x or its constit uents in both solid and liquid K2CO3. The barium ions are preferably d issolved in K2CO3, whereas potassium cations do not enter massively in to the bulk of the YBa2Cu3O7-x-phase. A eutectic-type phase diagram is supposed for the system K2CO3-YBa2Cu3O7-x. The so called ''green phas e'' - Y2BaCuO5 and a K-Cu-O compound have been found in the contact zo ne at 813 degrees C while a ''black phase'' layer with nominal composi tion Y1.6Cu2.8O5.4 has grown at 707 degrees C.