材料期刊网

Subsolidus phase relations of the constant copper oxide content (50 mol%) section in the PrO(11/6)-BaO-CaO-CuO system at 950 degreesC in air are investigated by means of X-ray diffraction analyses. The phase relations consist of I single-phase region, I two-phase region, 2 three-phase regions and 6 four-phase regions. Mutual substitutions among Pr, Ba and Ca in the Pr123 structure were studied in detail. The result indicates that Ba ions can be replaced exclusively by Pr ions, but not by Ca ions, whereas Ca ions can partially occupy the sites of Pr ions. The ionic radius plays a more important role than the chemical property for substitution among Pr, Ba and Ca ions in the Pr123 structure. (C) 2003 Elsevier B.V. All fights reserved.