REACTIVITY OF BASNO3 AS ADDITIVE AGENT WITH THE 211-YTTRIUM AND 123-YTTRIUM BARIUM CUPRATES

The reactions between BaSnO3 and YBa2Cu3O7 on the one hand and between BaSnO3 and Y2BaCuO5 (Y2BaCuO5 green phase and crude materials) on the other have been investigated in order to understand the role played b y BaSnO3 during sintering in the YBCO system. The formation of an inte rmediate phase, Ba2Sn[Sn1/3-xCuxY2/3]O-6-delta with the (NH4)(3)FeF6 s tructure has been evidenced. In the presence of this new phase the liq uid phase appears at lower-temperature YBCO. This results in a dramati c modification of the microstructure of the ceramic and of the distrib ution and the size of the Y2BaCuO5 inclusions with respect to the undo ped YBCO. Thus the reactivity between YBa2Cu3O7 and BaSnO3 explains th e role played by BaSnO3 in the MTG process of YBCO.