THE EFFECT OF NITRATES ON THALLIUM-BASED OXYCARBONATE SUPERCONDUCTORS

We have synthesised a series of compounds in both the (PbTl)Sr4Cu2O7(C O3)(1-y)(NO3)(y) (0.1 less than or equal to y less than or equal to 0. 5) and TlSr2Ba2Cu2O7(CO3)(1-y)(NO3)(y) (0.1 less than or equal to y le ss than or equal to 0.2) systems. We report the synthesis conditions o f these materials, an X-ray diffraction analysis of their structure an d the changes induced in superconducting behaviour produced by the int roduction of nitrate groups into the starting composition.