MOSSBAUER STUDIES OF FE-57 DOPED SINGLE-CRYSTALS OF GDBA2CU3O7-DELTA

Fe-57 Mossbauer effect measurements have been performed on single crystals of Fe-57 doped GdBa2Cu3O7-delta at various c-axis orientations and temperatures. The analysis of the data yields information on the sign and direction of V(zz), the direction of B(hf) with respect to V(zz) and the anisotropy of the f-factor for the individual observed three quadrupole doublets. From these data we conclude that the quadrupole doublet with DELTAE(Q) congruent-to 1.9 mm/s is due to Fe on a regular Cu(1)-site (4-fold oxygen coordination) with distorted local symmetry (V(zz) is not parallel to the c-axis), while the other quadrupole doublets have higher oxygen coordinations (higher Lamb-Mossbauer-factor).