Syntheses of the Bi(Pb)-2212 high-<i>T</i>_csuperconductor through a novel oxide nitrate route

Abstract

A novel route is presented for the syntheses of Bi2Sr2CaCu2Ox (Bi-2212) and (Bi,Pb)2Sr2CaCu2Ox (Bi,Pb-2212). Mixtures of oxides, nitrates and carbonates with approximate 2:2:1:2 metal ion compositions are dissolved in HNO3 and dried at 200 °C in air. Afterwards they are reacted under their in situ generated NOx atmosphere in a closed reactor (Staurohr). This reaction forces the system to form the nitrate precursors (Bi,Sr,Ca)2O2NO3/CuO and (Bi,Pb,Sr,Ca)2O2NO3/CuO, respectively. In the final reaction stage these mixtures are converted into Bi(Pb)-2212 under NOx discharge in air.