Interactions between YBa2Cu3O7-x and K2Co3

The interactions between YBa₂Cu₃O_7-x and K₂CO₃ have been studied using thermochemical methods, isothermal annealing of diffusion pairs, optical microscopy, X-ray diffraction, and microprobe analyses. The experiments have shown existence of solubility of YBa₂Cu₃O_7-x or its constituents in both solid and liquid K₂CO₃. The barium ions are preferably dissolved in K₂CO₃, whereas potassium cations do not enter massively into the bulk of the YBa₂Cu₃O_7-x-phase. A eutectic-type phase diagram is supposed for the system K₂CO₃–YBa₂Cu₃O_7-x. The so called “green phase” Y₂BaCuO₅ and a K–Cu–O compound have been found in the contact zone at 813 °C while a “black phase” layer with nominal composition Y_1.6Cu_2.8O_5.4 has grown at 707 °C.