Effect of repeated annealing on the synthetic and electrical properties of Bi2-(x+y)PbxAgy Sr2Ca2Cu3O10+δ electrically superconductor

الملخص

This research involved the preparation of Bi_2-(x+y)Pb_xAg_y Sr₂Ca₂Cu₃O_10+δ with different concentrations of (x,y) which are (x=y=0)(x=0.05,y=0.15)(x=y=0.1)(x=0.15,y=0.05) by the method of solid state reaction under hydrostatic pressure of 8 ton /cm²  and at annealing temperature of 1123K in presence of sufficient amount of oxygen.

In order to obtain an increase in the regularity of crystalline composite and also to obtain the best critical temperature, the annealing was repeated on these samples at 723K.

After X-ray diffraction (XRD) test to know how effective the partial substitution and repeated annealing is, it was obvious that the crystalline composite was of tetragonal type and the best substitution ratio is when (x=0.05,y=0.15) where the values of lattice dimensions were a=b=5.4056°A, c=37.4226°A, after repeating the annealing process on these samples ,the crystalline composite kept its type and with conspicuous increase in the length of c-axis, but the best sample after repeating the annealing was at ratio of (x=y=0.1) where the values of lattice dimensions became a=b=5.4030°A,c=37.5230°A when it was a=b=5.4011°A,c=37.0660°A before repeating the annealing .When the electrical properties of these samples was studied ,we noticed that the oxygen has an important role in increasing the critical temperature and we obtained the best critical temperature T_c=144K and that’s when x=0.05,y=0.15 while after repeating the annealing it was T_c=146K and that’s when x=y=0.1 and it was T_c=136K before repeating the annealing