The CuO-rich region of the system Y-Ba-Cu-O/K_2CO_3

摘要

Tablets of superconducting Yba_2Cu_3O_7-x, containing various excessive amounts of CuO (0, 2.38, 4.49, 5.69 g Cu per 100 g of the mixture), have been kept in contact with K_2 CO_3 at 903, 983, 1083 and 1209 K. Thereafter, cross-sections of the tablets and the contact zones have been studied by optical microscopy, X-ray diffraction, microprobe analyses, Raman spectroscopy and ICP-analyses. As a result of these investigations the existence of a low melting phase, probable a K-Cu-O compound, has been revealed. It has been found out that barium ions are dissolved with preference in potassium carbonate.