Funct. Mater. 2026; 32 (1): 33-40.

doi:https://doi.org/10.15407/fm33.01.33

Explorations of the impact of strontium substitution on selected physical characteristics of the HgBa1.6-xSrxLa0.4Ca2Cu3O8+δ superconductor

Taghreed Baqer Alwan1, Zainab J. Neamah 2, Laheeb A. Mohammed2, Mudatheer M. Al-Slivani 3, Kareem A. Jasim2

1 Department of Chemistry, College of Education for Pure Sciences, Ibn Al-Haitham, University of Baghdad, Iraq
2University of Baghdad, Department of Physics, College of Education for Pure Science, Ibn Al-Haitham
3 Al-Furqan University, College of Education for Pure Sciences, Department of Physics, Mosul, Iraq

Abstract: 

The study examines how partial substitution of strontium (Sr) for barium (Ba) in HgBa1.6-xSrxLa0.4Ca2Cu3O8+δ superconductors influences their structural and electrical properties. Samples with Sr concentrations of x = 0, 0.1, and 0.2 were synthesized using the solid-state reaction method. X-ray diffraction (XRD) analysis confirmed that all samples maintained the tetragonal phase characteristic of the Hg-1223 structure. As Sr content increased, there were notable changes in lattice parameters and mass density. These changes were attributed to the smaller ionic radius of Sr compared to Ba, leading to a reduction in the c/a ratio. This structural modification positively influenced the superconducting properties, as indicated by the critical temperature (Tc) measurements obtained using the four-point probe method. The Tc onset increased from 127 K to 139 K, while the Tc offset rose from 118 K to 126 K as Sr content increased from 0 to 0.2. Microscopic analysis through scanning electron microscopy (SEM) revealed a reduction in grain size as the Sr concentration increased. This reduction in grain size likely minimized insulating grain boundaries, potentially enhancing the superconducting behavior. Overall, the findings suggest that Sr substitution improves superconducting properties by altering the material′s microstructure and enhancing phase stability.

Keywords: 
Electrical Resistivity, Critical Temperature, X-Ray Diffraction, Tetragonal Structure And Superconductors.

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