The effect of using different y2o3 layers on the activation energy and ırreversibility line of mpmg ybco bulk at 1050 degrees c growth temperature
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KünyeKurnaz, S., Çakır, B., & Aydıner, A. (2018). The Effect of Using Different Y 2 O 3 Layers on the Activation Energy and Irreversibility Line of MPMG YBCO Bulk at 1050° C Growth Temperature. Journal of Superconductivity and Novel Magnetism, 31(10), 3167-3174. DOI: 10.1007/s10948-017-4551-1.
In this study, three kinds of YBCO samples which are named Y1, Y2 and Y3 were fabricated by a melt–powder–melt–growth (MPMG) method. The Y1 sample was placed into a platinum (Pt) crucible without Y2O3, the Y2 sample was located on a Al2O3 crucible with a freely poured Y2O3 powder and the Y3 sample was located on a Al2O3 crucible with a 1-mm-thick buffer layer of Y2O3. YBCO samples were investigated by magnetoresistivity (ρ–T ) measurements in dc magnetic fields (parallel to the c-axis) up to 5 T. The effect of the Y2O3 layer on the activation energy and irreversible flux of the samples was studied. The activation energies (U ) were determined using the Arrhenius activation energy law from ρ–T . The power law relationship for U with H −α was investigated. α was calculated to find out which defects were dominant in the samples. Irreversibility fields (Hirr) and upper critical fields (Hc2) were obtained using 10 and 90% criteria of the normal-state resistivity value from ρ–T curves. Irreversibility lines (ILs) were estimated from the equation Hirr ∼ (1−Tirr(H )/Tirr(0))n. The fitting results to giant flux creep and vortex glass models were discussed