Properties of YBCO superconductors prepared by ammonium nitrate melt and solid-state reaction methods

Ceramic YBCO superconductors were prepared by: (1) ammonium nitrate melt, (2) solid-state reaction methods and the properties of the samples obtained were compared. Under the same annealing conditions single phase YBCO was synthesized at a lower temperature by the former method. Moreover, at 900 degrees C Y-123 phase and the initially adjusted Y-211 additive could be formed using ammonium nitrate melt, but not with the solid-state method which leads Y-123 at a higher temperature (950 degrees C) without Y-211 additive. The samples prepared with ammonium nitrate melt technique have smaller grains, more grain boundaries and weak links causing low J(c), and wide superconducting transition temperature. Superconductors produced by this technique may be suitable for applications like magnetic field sensors that require small grains and reversible magnetization. (c) 2006 Elsevier B.V. All rights reserved.