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Tapes; doctor blade process; spiral growth.

Synthesis of H𝑔(Tl)Ba₂Ca₂Cu₃O_8+𝛿 superconducting tapes have been accomplished by annealing the precursor tape, Ba₂Ca₂Cu₃O_𝑦 (fabricated by doctor blade tape casting technique) in an environment of H𝑔(Tl) vapour. Characterization of superconducting HTSC tape sample was carried out through XRD, TEM, SEM and R–T measurements. Surface morphological investigations of the as-synthesized H𝑔(Tl)Ba₂Ca₂Cu₃O_8+𝛿 HTSC tapes by scanning electron microscope have shown the occurrence of curious growth characteristics resembling spiral like features. These growth spirals encompass nearly the whole grain suggesting that spiral growth led to the formation of small crystal like grains of superconducting material H𝑔(Tl)Ba₂Ca₂Cu₃O_8+𝛿. The likely mechanism for the generation of these screw dislocations has been elucidated in terms of incoherent coalescence of growth fronts formed from H𝑔(Tl):1223 and H𝑔(Tl):1234 nuclei.

Anjana Asthana¹ O N Srivastava¹

1. Department of Physics, Banaras Hindu University, Varanasi 221 005, India

Published

December 2001

Manuscript received

29 March 2001