Electronic structure of (Nd, Ce)2(Ba, Nd)2Cu3Oy

✍ Scribed by Yasushi Idemoto; Takemi Muroga; Kazuo Fueki

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 631 KB
• Volume: 210
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90973-t

✦ Synopsis

The dependence of Tc on oxygen content was determined for (Ndo.67Ceo.33)2 (Bao.67Ndo.33)2Cu3.0tO r It was found that superconduction appears in a range ofy = 9.10-9.16 and that Tc is enhanced remarkably by the increase of oxygen content. In an oxygen content range where superconduction appeared, the Ce valence was nearly + 4 and the Cu valence changed from 2.31 to 2.33. The conductivity was measured in a wide temperature range between Tc and 1200 K as a function of oxygen partial pressure. The high-temperature conductivity increased with increasing oxygen content. It was found that both carrier concentration and mobility are increased with oxygen content. The conduction at low temperatures was semiconductor-like, and increased with increasing oxygen content, where the energy gap EA-Ev between acceptor level and top of filled band approached zero.

One mol/1 solutions of Nd(NO3)3, Ce(NO3)3 and Cu(NO3)2, and a 0.25 mol/1 solution of Ba(NO3)2 were mixed so that a ratio Nd: Ce: Ba: Cu = 6: 2: 4: 9