Phase stability study of R2Ba4Cu7 O15 (247, R=Dy,Y, Er, DyY, GdY, and EuY) have been done for superconducting wire development. The oxygen pressure - temperature phase diagrams of R2Ba4Cu7O 15 superconductors have been investigated in the temperature range between 850 and 1025 °C and the pressure range between 1 and 50 atm. O2. The relative fraction of the phases: RBa2Cu3O7 (123), RBa2Cu4O8 (124), and 247, was determined by studying the intensity of the x-ray diffraction peaks of each phase. The condition at which the phase pure 247 exists was determined to be P = 10 atm. and T = 1025 °C. Under these conditions samples with larger size R = LaY, NdY, SmY, and Eu did not form pure 247 phase. Annealing at P = 200 atm. O2 and 400 °C was used to increase oxygen content of the as-synthesized materials and to induce superconductivity. The highest transition temperatures of 70 K were observed for R=Y compositions.
|Commitee:||Brown, Dennis E., Chmaissem, Omar, Dabrowski, Bogdan|
|School:||Northern Illinois University|
|School Location:||United States -- Illinois|
|Source:||MAI 51/03M(E), Masters Abstracts International|
|Subjects:||Condensed matter physics|
|Keywords:||Dysprosium, Gadolinium-yttrium, Rare earth barium copper oxide, Yttrium|
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