EMISSION MOSSBAUER STUDY OF OXYGEN DEFICIENT PRBA2CU3(CO-57)O-6+X

The variation of Mossbauer parameters as a function of oxygen content in (PrBa2Cu3(Co)O6+x)-Co-57 has been studied and compared to the resul ts of similar studies on (YBa2Cu3(Co)O6+x)-Co-57. It was found that th e Mossbauer isomer shift of (Co(Fe))-Co-57-Fe-57 dopant at Cu(1) site shows the same behaviour as for(YBa2Cu3(Co)O6+x)-Co-57 except that all isomer shifts are significantly higher than those for (YBa2Cu3(Co)O6x)-Co-57 and several other superconducting 1-2-3 compounds. These find ings are explained by the tendency of Pr(III) to form Pr(IV), which ca n be responsible for the absence of superconductivity, and charge tran sfer between the Cu(2)-O sheets and Cu(1)-O chains. It is also conclud ed that at high oxygen stoichiometries the Cu(1)-O chains have metalli c character for both compounds.