Phase relationships and cation disorder in RE(sub 1+x)Ba(sub 2-x)Cu(sub 3)O(sub 7+(delta)), RE = Pr, Nd, Sm, Gd

摘要

Unlike Y123 which forms only a stoichiometric compound, the light arare earth elements (LRE) form a solid solution LRE(sub 1+x)Ba(sub 2-x)Cu(sub 3)O(sub 7+(delta)) (LRE123ss), with increasing substitution of the LRE(sup 3+) for the Ba(sup 2+) as the ionic radii of the LRE increases. The sub-solidus phase relationships around the LRE123ss change for La, Pr and Nd, but are similar for Sm and Gd. However, the solubility limit decreases with decreasing ionic radii. In addition, the solubility limits for Sm and Gd are strongly influenced by PO(sub 2) during high temperature annealing. The range of solubility is, for any given LRE system, strongly dependent on the oxygen partial pressure (PO(sub 2)) providing a new means by which to control the microstructure in the RE123 system.