YBa2(Cu1-xFex)(3)O-7-d annealed in an Ar atmosphere, then reoxygenated
at various temperatures, has been studied by Mossbauer spectroscopy a
t 300 K and low temperature with and without an applied field of 5.5 T
. The results are interpreted as being due to Fe clustering remaining
in the chains rather than a significant transfer to the planes.