A study of the effect of KClO₃ addition on the AC susceptibility and micro structure of high-temperature (T_c^onset at 105 K) YBCO ceramic superconductors

Bulk Y₁Ba₂Cu₃O_y superconductors with KClO₃ or K₂CO₃ additives were synthesized by a solid state reaction method. The influence of additives on the AC susceptibility, morphology and microstructure of samples with nominal compositions Y₁Ba_2-xK_xCu₃O_y, Y₁Ba₂Cu_3.5-xK_xO_y, Y_1-0.2xBa_2-0.2xK_xCu₃O_y, (x=0.2) were investigated. Experimental results showed a promoting effect of the additives on the formation of 123 phase in air atmosphere. Only traces of potassium were observed in all samples after the final backing, but chlorine was remained in the material. The superconducting transition temperature for all KClO₃-doped samples was found to be higher than that for K₂CO₃-doped and undoped Y₁Ba₂Cu₃O_y (YBCO). KClO₃-doped Y₁Ba_1.8K_0.2Cu₃O_y with T_c^onset at 105 K was obtained. The comparison of characteristics for samples with various potassium compound in the initial batch demonstrated that each additive had a specific effect on _X(T), ΔT_C and microstructure of YBCO high-temperature superconductors (HTSC). The results were discussed in terms of different interaction in which KClO₃ and K₂CO₃ participate up to 900°C.