Influence of powder processing procedure on the superconducting behaviour of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-y</SUB> ceramics

In order to synthesize YBa2Cu3O7-y powder, we first coprecipitate yttrium and barium by adding ammonium carbonate to a solution of barium and yttrium chlorides mixed in the 2:1 ratio at the molar level. Ceramics, prepared from powders obtained by calcining the coprecipitated powder with copper oxide, exhibits a very sharp drop in resistivity near 110 K with Tcmidpoint of 107 K and a resistivity anomaly at 260 K