Nd 2O 3 doping of top-seeding-melt-texture-growth-processed YBa 2Cu 3O 7− δ ceramics

Abstract

The NdBa 2Cu 3O 7− δ compound exhibits better critical current densities under high magnetic field than YBa 2Cu 3O 7− δ . As it has been shown that the use of dopants such as CeO 2, PtO 2 or SnO 2 can increase the superconducting properties of YBa 2Cu 3O 7− δ , the effects of neodymium oxide additions as a dopant are envisaged. The SEM study of the microstructure of the samples shows that no refinement of the Y211 phase occurs due to neodymium additions but without cancelling the refinement due to CeO 2 additions. No secondary phases containing neodymium have been observed. EDS analyses show that neodymium is present in both the Y123 matrix and the Y211 particles, about twice more in the Y211 particles than in the Y123 matrix. The YBa 2Cu 3O 7− δ usual annealing process (430 °C—150 h in flowing oxygen for a 16 mm diameter pellet) leads to T c(onset) of 91 K with large transition and poor critical current densities. A new annealing process at lower temperatures (between 430 and 300 °C) gives samples with sharper transitions ( T c(onset) of 91.4 K) and good critical current densities (around 50,000 A cm −2 at 77 K and 0 T). However these critical current densities are similar to those usually obtained for neodymium undoped compositions.