The Conductivity Mechanism in an Hg-Ba-Ca-Cu-O High-Tc Superconductor

Abstract

This research carried out experiments on the superconducting compound HgBa2Can−1CunO2n+2+δ at n = 2, 3. The samples were prepared using a sealed quartz tube. XRD analyses were used to determine the crystal structure and their parameters for both Hg-1212 and Hg-1223. Many software packages were used to refine and simulate the crystal structures. It was clear that the final phase in all cases was a tetragonal phase with a space group symmetry P4/mmm (123), and shrinkage along the c-axis of about 0.2 from the theoretical value. There was a slight variation in the basal plane axis and a sharp increase in the c-axis as a function of n. The presence of an octahedron structure within the unit cell is the origin of the charge reservoir, and increasing the number of octahedrons per unit cell is the reason to increase the concentration of the electronic charges per unit cell. Iodometric titration was done to show the excessive oxygen content, during the creating of tetrahedron structures. The last reason is to determine the amount of oxygen insertion within the structure. Resistivity measurement was necessary in order to determine the critical temperatures and related resistivity, creating the correlation with Miller indices and lattice constants. At the same time, the tetrahedrons are the main topics in developing the conductivity. It was clear from the electrical resistivity that the critical temperatures were 115 and 125 K for Hg-1212 and Hg-1223, respectively. These critical temperatures were in agreement with the data from the vibrating sample magnetometer (VSM). There were magnetic susceptibilities in both phases, i.e., χ = − 0.25 × 10−2 and − 0.41 × 10−2 for the Hg-1212 and Hg-1223 phases, respectively. It was concluded that many parameters were related to the conductivity and magnetic susceptibility of both phases. The induced magnetic field is 99.75% for n = 2, and 99.59% for n = 3. This result is in agreement with the results of penetration depth for both systems that showed greater value for n = 3 than for n = 2.