Effect of praseodymium substitution in YBa2Cu4O8 (1:2:4)

✍ Scribed by H.B. Liu; D.E. Morris; A.P.B. Sinha; George H. Kwei

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 377 KB
• Volume: 223
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90693-9

✦ Synopsis

Pr substituted YBa2Cu4Os ( 1 : 2: 4) has been synthesized by a solid-state reaction at 930 ° C-950 ° C in 200 bar oxygen pressure. Pr could be substituted only up to 20% i.e., Yo.sPro.2Ba2Cu4Os. Tc decreased with increasing Pr; however, Tc could be restored by co-substitution of Ca along with Pr which was possible up to Pr= 0.2 and Ca = 0.1. XANES indicated the presence of Pr 3+ but not Pr 4÷. In 1 : 2: 4, Tc depends on the rare-earth ion size, and Pr 3+ ions cause only a small additional suppression of Tc below that expected from the size of Pr 3+. The large "Pr effect" in the suppression of Tc of 1 : 2: 3 is thus a special property of the 1 : 2: 3 structure.