Observation of curious spiral growth features in Tl doped Hg bearing high temperature superconducting tapes

[摘要] Synthesis of Hð‘�??(Tl)Ba₂Ca₂Cu₃O_{8+ð›�?} superconducting tapes have been accomplished by annealing the precursor tape, Ba₂Ca₂Cu₃O_ð‘�? (fabricated by doctor blade tape casting technique) in an environment of Hð‘�??(Tl) vapour. Characterization of superconducting HTSC tape sample was carried out through XRD, TEM, SEM and Râ€�?�T measurements. Surface morphological investigations of the as-synthesized Hð‘�??(Tl)Ba₂Ca₂Cu₃O_{8+ð›�?} 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 Hð‘�??(Tl)Ba₂Ca₂Cu₃O_{8+ð›�?}. The likely mechanism for the generation of these screw dislocations has been elucidated in terms of incoherent coalescence of growth fronts formed from Hð‘�??(Tl):1223 and Hð‘�??(Tl):1234 nuclei.

[学科分类] 材料工程

[关键词] Tapes;doctor blade process;spiral growth.