Systematic Investigation of the Pr-Ba-Cu-O Phase Diagram

This dissertation reports on an investigation into the longstanding mystery of why praseodymium barium cuprate is the only member of the $RBa2Cu3O7-y$ family (which includes $RBa2Cu4O8$ and $R2Ba4Cu7O15$) that has been synthesized with orthorhombic structure that is non-superconducting, juxtaposed with several contradictory reports of superconductivity. I walk through all of the possible contributors towards anomalous superconductivity based on existing reports: aluminum contamination/doping, alternate phases, and different stoichiometries. For all of these options, I find that the compounds are non-superconducting via magnetic and electronic measurements, only leaving the possibility of stress/strain induced superconductivity unexplored. In the process, I determine that the heat treatment reported to yield superconductivity in \PBCO (Pr123) results in the formation of significant quantities of $Pr2Ba1Cu1O5$ (Pr211) to form. I further establish that the three compounds: \PBCO, \PrTFS (Pr247), and $PrBa2Cu4O8$ (Pr124), belong to a single incommensurate structure.