Nd1+xBa2−xCu3Oy processed in high pressure oxygen. Effects of enhanced oxygen uptake on structure and superconductivity

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

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 650 KB
• Volume: 224
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90259-3

✦ Synopsis

The Tc of Nd 1÷xBa2_xCuaOy (0.1 ~<x~ 0.6) has been increased by synthesizing and annealing the compounds in 200 bar oxygen pressure. The oxygen content, y, increases to compensate the effect of Nd a+ substitution and the formal average copper valence (FACV) remains unchanged at ~ 2.3 throughout the composition range. Although the FACV remains constant, Tc falls systematically with increasing x, suggesting that Nd 3+ at the Ba 2+ site binds a portion of holes. Thermogravimetric data show an increasingly negative slope of the weight-temperature plot with larger x, indicating that the enthalpy for binding the oxygen in the CuO chain increases when oxygen per formula unit increases beyond seven.