Bulk Y1Ba2Cu3Oy 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 Y1Ba2-xKxCu3Oy, Y1Ba2Cu3.5-xKxOy, Y1-0.2xBa2-0.2xKxCu3Oy, (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 Y1Ba2Cu3Oy (YBCO). KClO3-doped Y1Ba1.8K0.2Cu3Oy with Tconset 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), ΔTC 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.
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