Impact of Pr doping on superconductivity in Bi2PrxCa3-xCu2O8+delta

A systematic study on the nature of Pr doping in Bi2PrxCa3-xCu2O8+delta (0. 2 less than or equal to x less than or equal to 0.6) has been made on films grown by laser ablation. These films are a metastable Bi-2212 phase which has net yet been grown in this doping range by other methods. The film with x = 0.2 shows the highest zero-resistance temperature (T-cz) of about 65 K . T-cz of the films decreases with increasing Pr content yielding a metal-t o-insulator transition for x > 0.5. By analyzing x-ray photoelectron spectr a we show that Pr is trivalent. From this we are able to demonstrate that t he variation of T-cz with doping is predominantly due to hole filling induc ed by the trivalent Pr.