Interactions between YBa 2 Cu 3 O 7‐ x and K 2 Co 3

The interactions between YBa 2 Cu 3 O 7‐ x and K 2 CO 3 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 YBa 2 Cu 3 O 7‐ x or its constituents in both solid and liquid K 2 CO 3 . The barium ions are preferably dissolved in K 2 CO 3 , whereas potassium cations do not enter massively into the bulk of the YBa 2 Cu 3 O 7‐ x ‐phase. A eutectic‐type phase diagram is supposed for the system K 2 CO 3 –YBa 2 Cu 3 O 7‐ x . The so called “green phase” Y 2 BaCuO 5 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 1.6 Cu 2.8 O 5.4 has grown at 707 °C.