Application of top seeding in the melt processing of Nd₁₂₃ thick films on YSZ substrates: I buffer layer optimisation

A new concept of a buffer layer in superconducting thick film technology was tested. The idea is based on increasing the NdBa2Cu3Ox melt viscosity at the processing temperature near the substrate by using higher ratios of Nd4Ba2Cu2Oz solid phase in the first screen printed pass which is considered as a buffer layer. Different compositions, thicknesses and thermal schedules were used to optimise the buffer layer. The optimised buffer layer was employed in the fabrication of NdBa2Cu3Oy thick films on yttria stabilized zirconia (YSZ) substrates using the top seeding melt growth (TSMG) technique. Using the buffer layer was effective in preventing a large amount of liquid (BaCuO2-CuO) from severe interaction with the substrate during the prolonged time in the TSMG technique. Consequently, a large superconducting single domain was obtained. Thick films were melt processed in 0.1% O-2 in Ar atmosphere to suppress the Nd1 + xBa2 - xCu3Oy (Nd-123SS) solid solution formation. The produced thick films have high transition temperature (T-C) and improved microstructures. (c) 2005 Springer Science + Business Media, Inc.