Synthesis and properties of YBa 2Cu 3O 7−δ made by a modified hydroxycarbonate method

Abstract

YBa 2Cu 3O 7−δ was synthesised using a solution method. The coprecipitation of the stoichiometric amounts of nitrate solution of yttrium, barium and copper was performed using a mixture of NaOH, Na 2CO 3 and H 2C 2O 4 in a molar ratio 5:1:1 as precipitation agent. The as-obtained precursors have a copper deficiency of 0.1 with respect to the nominal stoichiometry of the starting solution. The mechanistic study of the product formation has revealed that in these atomically mixed precursors the individual components have a different behaviour with respect to those in a mechanical mixture. The final products was obtained after heat treatment at 950°C for 6 h in oxygen atmosphere. The product was analyzed by XRD, SEM, EDXS and four probe DC resistivity measurements. The as-synthesised YBCO has shown good superconducting properties T c( R = 0) = 90.5 K and ΔT = 1 K. This method was used with success in the fabrication of YBCO target for laser ablation.