CHARGE-CARRIER DISTRIBUTION IN Y1-ZCAZBA2CU3OX

We have performed polarized reflection measurements on the (001) plane of various single domain crystals of Y1-zCazBa2Cu3Ox with different C a and oxygen content. Using the in-plane anisotropy of the optical pro perties, we could separate the contribution of the Cu-O layers and the Cu-O chains to the electronic transport properties. It was found that the additional carriers introduced as a result of the Ca doping only appear in the Cu-O layers. while the doping of the chains is even redu ced because of an increase of oxygen vacancies with increasing Ca dopi ng for samples with an oxygen content close to seven. The superconduct ing transition temperature T-c could be correlated with the free carri er concentration in the Cu-O layers, indicating a comparable phenomeno n oi overdoping in the 1-2-3 compound as it has been found in other hi gh T-c cuprates.