Destabilisation of 124 and 247 phases of Y-Ba-Cu-O by Fe substitution at elevated oxygen pressures

✍ Scribed by D.E. Morris; A.P. Marathe; A.P.B. Sinha

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 397 KB
• Volume: 169
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(90)90581-x

✦ Synopsis

Single phase iron-substituted 124, (YBa2Cu4_xFexOy) has been obtained in the range of 0 ~ x ~< 0.05 at oxygen pressure of 200 bar and 100 bar. Greater Fe substitution at elevated P(O2) destabilised the 124 and 247 phases in favor of a tetragonal 123 phase . The solubility of Fe in FeT-123 phase increases with oxygen pressure. The lattice parameters do not change significantly with Fe content and P(O2). The formal average copper valency (FACV) of single phase FeT-123 samples is high (e.g. FACV = 2.58 for x = 0.65 ). The reduction of Tc caused by Fe substitution in YBa2Cu3_xFexOy is about 6 K/%x over the range (0 ~< x ~< 0.2 ) for samples prepared at P(O2 ) = 200 bar and cooled slowly under pressure.