THE EFFECTS OF SNO2 ADDITION ON THE GROWTH OF Y2BACUO5 AND YBA2CU3O7-DELTA PHASES IN THE Y-BA-CU-O SYSTEM

With YBa2Cu3Sn0.1O7-delta and Y2BaCu1.8Sn0.1O5+delta specimens, the ef fect of SnO2 addition on the 211 phase growth is investigated. The add ition of SnO2 is considered to make the nucleation of the 211 phase oc cur favourably. In order to study the effect of SnO2 addition on 123 p hase growth in the Y-Ba-Cu-O system, a 0.1 SnO2-added 123+Sn compact i s coupled with the SnO2-free 123 compact(s). The 123 phase forms in th e surface region of the 123+0.1 Sn compact and grows toward the interi or of this compact and toward the SnO2-free 123 compact(s). It is cons idered that the addition of SnO2 and faster cooling in the surface reg ion than in the inner region of the sample make the nucleation of the 123 phase occur favourably in the surface region of the 123+0.1 Sn com pact.