THE EFFECT OF YTTRIUM ON THE CA AND SR PLANES OF Y-DOPED BI2SR2CA1CU2O8

Photoemission spectromicroscopy experiments on a series of Y-doped Bi2 Sr2Ca1Cu2O8 single crystals show that the doping changes the valence o f copper as required for the observed modification of the critical tem perature. The doping, however, affects with substitutional reactions n ot only the CaO planes, but also the SrO planes.