MOSSBAUER AND PHASE INVESTIGATIONS OF YBA2CU3-XSNXO7-DELTA 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1)

YBa2Cu3-xSnxO7-delta (0 less than or equal to x less than or equal to 1) samples were synthetized. For x < 0.18, the orthorhombic samples ar e superconducting, T-c being nearly constant. From x greater than or e qual to 0.06 a new disordered perovskite - like phase is detected. Fro m Mossbauer spectra Sn is always 4(+). Two doublets are necessary to f it the pure 123 spectrum in agreement with only one of the various pro posed solutions. The population of the two doublers are discussed with regard to the Cu sites. It is therefore possible to deduce approximat ively the proportions of the two phases in agreement with X-rays resul ts.