THE INFLUENCE OF SINTERING AND Sb CONTENT ON THE FORMATION OF HIGH TEMPERATURE SUPERCONDUCTING PHASE IN Bi(Pb)-Sr-Ca-Cu-O SYSTEM

Abstract

Six different compositions in ( Bi 1.5 Pb 0.5−x Sb x) Sr 2 Ca 2 Cu 3 O y (with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) have been prepared by the solid state reaction method. Sintering at different temperatures (between 800–860° C) and time periods has been carried out in order to study its effect on T c values. The samples have been characterized by x ray powder diffraction (XRD), Scanning Electron Microscopy (SEM) and measurement of resistance at various temperatures. The study reveals that the incorporation of Sb up to x = 0.2 promotes the formation of a high-T c 2223 phase and large sintering time helps in reducing the number of unwanted phases. Compositions with x ≥ 0.3 result in the formation of a new monoclinic "4441 phase" (along with 2223 and 2212 minor phases) which is non-superconducting down to 77 K. Sintering time at 860°C for samples with x = 0.0, 0.1, 0.2 and 0.3 affects the respective T c values and the maximum values observed are 94 K, 96 K, 100 K and 87 K, respectively. The samples with x = 0.4 and 0.5 do not superconduct up to 77 K.

THE EFFECT OF 5% Sb DOPING ON HIGH Tc SUPERCONDUCTIVITY IN (Bi, Pb)2Sr2Ca2Cu3Oy COMPOUND

“…The addition of such a small proportion of Sb helps in increasing the high T c 2223 phase in the product when sintered for 643 hours at 860 • C and using a slow cooling procedure. From the present study and also from our previous investigations on the Bi-Pb-Sb-Sr-Ca-Cu-O system, [18][19][20] it may be concluded that the addition of a small amount of Sb, say 5%, to the Bi 1.5 Pb 0.5 Sb 2 Ca 2 Cu 3 O y is beneficial to obtain a high proportion of high T c 2223 phase. Simultaneous replacement of Bi by Pb and Sb normally results in a multiphase product.…”

“…Some of these results of this study have been reported elsewhere. [18][19][20] We have also observed that Sb content, annealing time and temperature all affect the quality of the high T c superconductivity phase. In the present study, we have synthesized a composition of Bi 1.5 Pb 0.5 Sr 2 Ca 2 Cu 3 O y with an addition of 5% Sb using the solidstate reaction method.…”

“…12,13,[15][16][17][18][19][20] The role of Sb along with Pb in Bi systems, the presence of the new "4441" phase and the effect of annealing time on superconductivity still remains unclear. Our group has carried out a detailed study to understand the effect of annealing time and Sb content on T 0 c .…”

Synthesis and characterization of antimony-doped Bi-based superconducting materials

“…For the high-Tc phase the highest intensity peak for the sample (A1) was found to be 735 counts per second (CPS) at 2θ value of 30 • and for sample (A2), the highest intensity peak was obtained at 859 CPS at 2θ value of 28 Figs. 1-3 show that a sharp and intense peak corresponding to the high-Tc (2 2 2 3) phase [10,23], appearing at low 2θ value of nearly 5 • , gradually increases in its intensity with increase in antimony content from x = 0.02 to 0.08 and the maximum intensity of 647 CPS was obtained for this peak at 2θ value of 4.72 • for the sample (A5) having x = 0.08. However, on further increase in antimony content such as x = 0.15 for sample (A6) as shown in Fig.…”