Irreversibility line of y2o3 layered YBa2Cu3O7-x compound

In this study, five kinds of YBCO samples using Melt-Powder-Melt-Growth (MPMG) method which are named Y1040_buffer, Y1050_empty, Y1050_powder, Y1050_buffer and Y1060_buffer were fabricated. The compacted powders were located on a crucible with a buffer layer of Y2O3 and a crucible with Y2O3 powder freely poured to avoid liquid to spread on the furnace plate and also to support crystal growth. YBCO samples were investigated by resistivitytemperature (ρT) and magnetization temperature (MT) measurements in dc magnetic fields (parallel to caxis) up to 5 T. Irreversibility fields (µ0Hirr) and upper critical fields (µ0Hc2) were obtained using %10 and %90 criteria of the normal state resistivity value from ρT curves. MT measurements were carried out using the zero field cooling (ZFC) and field cooling (FC) processes to get irreversible temperature (Tirr). Irreversibility lines were estimated from the equation µ0Hirr ~ (1Tirr(H) / Tirr(0))n. Fitting of results to giant flux creep and vortex glass models were discussed. At the fabrication of MPMG YBCO, optimized temperature for crystal growth was determined to be around 10501060°C.