Studying the partial substitution of Pb instead of bi-o on electrical properties of the BBCCO system

This study investigates the effect of chemical substitution on the physical properties of the superconducting ceramic composite Bi2₋ₓPbₓBaCa₁.₈₅Sb₀.₁₅Cu₃O₁₀₊δ with varying amounts of lead substitution (x=0.0, 0.1, 0.2, 0.3, 0.4). The main objective is to optimize the substitution conditions to enhance the structural and electrical properties of the composite and obtain the maximum superconducting transition temperature (high temperature). The samples were produced by the solid-state reaction (SSR) method under controlled conditions to facilitate gradual atomic diffusion. The four-probe technique was used to investigate the electrical resistivity as a function of temperature, facilitating the calculation of the critical transition temperatures (Tc) and energy gap (Eg) values ​​for different substitution levels. The results show that all samples exhibit superconducting (metallic) properties at 780 °C. In comparison the best and most optimal sample was identified using the SSR method, and under optimal conditions compared to the samples with substitution (x=0.4), it had the highest critical transition temperature (Tc=121.8 K), the highest energy gap (Eg=0.035192588 eV), the lowest bandwidth ΔT(K)=1.2, and the highest hole concentration P(Hole)=0.16. These changes reflect the improved superconducting properties upon substitution of lead at the sample (x=0.4), making this composition ideal for high critical temperature applications.