The effect of high temperature sintering on the Tc of Tl1Ba2Can−1CunOx system

• Published in: Solid state communications 1990-05, Vol.74 (8), p.789-795
• Main Authors: Saini, K.K., Sharma, C.P., Ekbote, S.N., Suri, D.K., Asthana, Pavas, Nagpal, K.C., Chanderkant, Chandra, Subhas
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Superconductivity; Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/0038-1098(90)90936-6

The effect of high temperature sintering (T ≅ 970°C) has been studied on the Tl1Ba2Can−1CunOx systems where n varies from 1 to 5. It has been found that under optimised conditions of preparation the final phase composition obtained can vary considerably from the starting or nominal composition. XRD studies have revealed that in the case of n = 1 and 2, the Tl1 nominal composition 1201 and 1212 have converted into 2201 and 2212 with a = 3.85 Å and c = 23.23 Å for 2201 and a = 3.86 Å and c = 29.04 Å for 2212, with an enhanced Tc for 2201 (Tc ∼ 97.2K) over previously reported Tcs. The other nominal compositions of n = 3, 4 and 5 (1223, 1234 and 1245) were showing only the Tl1 series behaviour with slightly enhanced Tzeroc and Tonsetc. The XRD studies showed that in all the above phases a = 3.86 Å and c = 15.5 Å. The low angle peak appears at 2π = 5.25° indicating the formation of n = 3 or Tl1Ba2Ca2Cu3Ox compound.