Synthesis and Structure of PrBa2Cu2Co1O7+y: A New Nonsuperconducting Orthorhombic 123 System1

✍ Scribed by M.S. Hegde; S. Ramesh; T.S. Panchapagesan

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 341 KB
• Volume: 102
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1993.1039

✦ Synopsis

(\mathrm{PrBa}{2} \mathrm{Cu}{3-1} \mathrm{Co}{x} \mathrm{O}{7+r}(0<x<1)) crystallizes in tetragonal structure for small values of (x(0.1<x<0.3)) and in orthorhombic struclure for (0.4<x<1), as revealed by (X)-ray and electron diffraction studies. The end member (\mathrm{PrBa}{2} \mathrm{Cu}{2} \mathrm{CoO}{7,4}) shows orthorhombic to tetragonal structural transition with decrease in oxygen content just as (\mathrm{YBa}{2} \mathrm{Cu}{3} \mathrm{O}{7-y}(123)) and (\mathrm{PrBa}{2} \mathrm{Cu}{3} \mathrm{O}{7-v}(\operatorname{Pr} 123)). From the structure and reactivity, the (\mathrm{Co}) ion in (\mathrm{PrBa}{2} \mathrm{Cu}{2} \mathrm{CoO}{7+r}) is suggested to occupy the (\mathrm{Cu}(2)) (plane (\mathrm{Cu}) ) position and the oxygen excess over 710 occupy the ((0,0,1 / 2)) position between the (\mathrm{CuO}{2}-\mathrm{CuO}{2}\left(\mathrm{CoO}_{2}\right)) sheets. The structure supports two types of labile oxygen, one associated with the chain (\mathrm{Cu}(1)) and the other in the interlayer associated with the Co ion, as revealed by anaerobic oxidation of ammonia. 1993 Acatemic Press. Inc.