Reactive-field-assisted-sintering of freeze-dried powders in the BSCCO system

The reactive-field-assisted-sintering technique (RFAST) has been applied to freeze-dried decomposed precursor powders with a starting cation composition of Bi:Pb:Sr:Ca:Cu =1.7:0.3:2.0:2.5:3.5 Bi:Pb:Sr:Ca:Cu = 1.7:0.3:2.0:2.5:3.5. A short time (<15 min) RFAST treatment at 800-900 °C did not lead to the formation of Bi₂Sr₂Ca₂Cu₃O_10+x (2223-phase). But RFAST was favourable to Bi₂Sr₂CaCu₂O_8+y (2212-phase) formation particularly in samples with a low content of the 2212-phase in the precursor powder. Heat treatment (HT) after RFAST showed that the 2223 phase could form more rapidly than in freeze-dried pressed and sintered pellets produced by the traditional technique. The resultant ceramics after 70 h of annealing contain 75% 2223-phase and have T_{c(R = 0)} = 100.7 K, T_c = 109.5 K and ΔT_c = 22.4 K.