SUPERCONDUCTING PROPERTIES AND MICROSTRUCTURE OF YBCO HTSC MATERIALS WITH K2CO3 ADDITION

The influence of K2CO3 additive on the superconducting properties and microstructure of samples with nominal compositions Y1-0.2xBa2-0.2xKxC u3O7-y, Y1Ba2Cu3.5-xKxO7-y, Y1Ba2-xKxCu3O7-y, (x = 0 to 1.50), were in vestigated. Only traces of K (1x10(-2) wt.%) were observed in all samp les after the final baking and no proof could be found for alkali meta l cations participating in the Perovskite crystal cell. Potassium carb onate eliminated the CuO second phase from the system, because of a KC u-compound formation which evaporated above 900 degrees C. The influen ce of the K2CO3 was positive for x = 0.40 to 0.75 where we observed ho mogenous grain-size ceramic structure and HTSC Y1Ba2Cu3Oy samples with values of T-C=93.4 K and Delta T=1.5 K.