One step synthesis of Bi(Pb)-2223 phase in Bi(Pb)-Sr(Ba)-Ca-Cu nitrate freeze dried powder

One step synthesis of the superconducting Bi(Pb)-2223 phase during heat tre atment for non-equilibrium decomposition of the freeze dried Bi:Pb:Sr:Ba:Ca :Cu = 1.8.0.4: 1.8:0.2:2.2:3.0 nitrate powder has been studied. The heating rate was similar to 100 degrees C min(-1) and samples were maintained in a ir at 848 degrees C for 0, 5, 10, 20, 30, 60, 90, 240 and 1080 min. Each ba tch was investigated by x-ray diffraction analysis and ac magnetic suscepti bility chi'(T). Evolution of phases and kinetics of phase formarion-decompo sition processes were discussed. similar to 80% of Bi(Pb)-2223 has formed i ndicating the possibility of lowering the processing time of the freeze dri ed precursor powders by one order of magnitude comparative to the multistep synthesis route (from hundreds to tens of hours). A 30 min heat treatment step at 840 degrees C performed on the way up to the synthesis temperature is a forthcoming operation in order to block the formation of secondary und esired phases (e.g. (Ca1-xSrx)(14)Cu24O41).