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Abstract
Study of effects of the chemical substitution on the physical properties of
superconductor materials is of great importance to improve the superconducting
properties. Many types of substitution have been performed in different high
temperature superconductors and the results depend on the probable site occupancy.
The replacement must be between ions of equivalent size. The substitution by the rare
earth elements in high temperature superconductors has special interest for basic and
applied physics. Usually, the rare earth elements substitute directly in the CuO2-plane
itself, or indirectly through the substitution in the Ca-site are well known to alter the
concentration of carriers occurs through the Cu-O network. This has a great importance
for developing new superconducting materials conceived for diverse applications.
In this work, the effect of partial substitution of Ca2+ and Cu2+ ions by Ho3+ and
Sc3+ ions, respectively, on (Bi,Pb)-2223 phase has been studied. For this purpose,
superconducting samples of types Bi1.8Pb0.4Sr2Ca2.1-x HoxCu3.1O10+δ phase with 0.000
≤ x ≤ 0.200 and Bi1.8Pb0.4Sr2Ca2.1Cu3.1-xScxO10+δ phase with 0.000 ≤ x ≤ 0.175 were
prepared using the standard solid-state reaction technique. The prepared samples were
characterized using X-ray powder diffraction (XRD), scanning electron microscopy
(SEM) for phase analysis and microstructure examination, respectively. The
elemental stoichiometric of the prepared samples was determined using energy
dispersive X-ray (EDX). The X-ray data clarify that the partial substitution of Ca2+
and Cu2+ ions by Ho3+ and Sc3+ ions, respectively, does not influence the tetragonal
structure of (Bi,Pb)-2223 phase. Moreover, X-ray analysis showed that the low Hocontent
enhanced the phase formation up to x = 0.025 and for Sc-content up to x =
0.125. In addition, the surface morphology of the prepared samples displayed the
decrease in the porosity among the grains, increased the microstructure density and
grain size resulting in the improvement of inter-grain connectivity up to x =0.025 and
x = 0.125 for Ho- and Sc-contents, respectively. On the other side, EDX results showed
elemental contents very close to the starting values.