Synthesis and characterisation of the thallium-substituted superconductingcuprate Hg1-xTlxBa2Ca2Cu3O8+delta

The objective of this research is the development of chemical routes for th e preparation of high-temperature superconducting powders. A simple sol-gel synthesis technique for preparing the superconducting compound Hg1-xTlxBa2 Ca2Cu3O8+delta (Hg,Tl-1223) has been refined. A systematic study of the inf luence of synthesis conditions on the phase purity of the obtained supercon ducting material is described, We have demonstrated that superconducting Hg 1-xTlxBa2Ca2Cu3O8+delta phase of good quality can be obtained by this sol-g el synthesis method. Replacing Hg by Tl in the bulk material significantly increased the superconducting transition temperature. An as-prepared sample showed T-C(onset) 136 K, but after oxygen treatment the critical temperatu re of Hg1-xTlxBa2Ca2Cu3O8+delta superconductor increased to 140 K, Copyrigh t (C) 2000 John Wiley & Sons, Ltd.