Characterization of YBa2Cu3O7-x made by a sol-gel process using nitrate salts and sodium hydroxide

A sol-gel processing of YBa2Cu3O7-x superconductor using metal nitrate salts and sodium hydroxide as the starting materials has been investigated because of the need to produce pure, homogeneous superconducting materials. Homogeneous colloidal sols have been obtained by the precipitation process of the mixed metal cations with precipitation anions of hydroxide at the solution basicities of pH 13 at room temperature. The calcined powders have been investigated using IR and XRD such that the YBa2Cu3O7-x phase started to be formed ca.750deg C and completeed the formation ca.800deg C when heated for 12 hours. The sinterings of the calcined powders have been investigated using dilatometry such that the tetragonal-orthorhombic phase transition during the cooling stage occurred ca.680deg C. The resulting sample exhibited a sharp Tc (ΔTc=1.2K) at 94K. (Author)