Thermal stability of NdBCO/YBCO/MgO thin film seeds

Thermal stability of the Nd 1+ x Ba 2− x Cu 3 O 7− δ (Nd-123 or NdBCO) thin films deposited on MgO substrate, with YBa 2 Cu 3 O 7− δ (Y-123 or YBCO) buffer layer (NdBCO/YBCO/MgO thin film), has been experimentally studied in order to determine the optimal film thickness acting as seed for bulk YBCO growth. YBCO bulk superconductors with Y 2 BaCuO 5 (Y-211) and CeO 2 addition were prepared by the top seeded melt growth process in a chamber furnace using NdBCO/YBCO/MgO thin film seeds of different thicknesses (200–700 nm with 20 nm YBCO buffer layer) and different maximum temperatures, T max . The maximum temperatures varied in the range of 1040 °C–1125 °C. The highest thermal stability 1118 °C was observed in the case of NdBCO/YBCO/MgO thin film of 300 nm thickness. These results are corroborated with differential scanning calorimetry and high temperature x-ray diffraction measurements, as well as microstructure observations.