The Effects of Substrate Material, Quenching and Annealing on the Properties of High Temperature Superconductor BSCCO (Bi-2212) Thick Tapes
Abed Al-Kariem Saleh
The effects of substrate material and heat treatment conditions on the electrical and thermal properties for partially melt-solidified superconducting tapes BSCOO (2212), grown on single crystal MgO and Ag MgO substrates m were investigated. Results show that the resistivity of the normal state varies with the size and orientation of the grains. It is found that larger grains lower both the concentration of second phases and the grain boundaries, hence decreasing the resistivity of the normal state and enhancing the critical current density of the superconducting state. Also, the material of the substrate has no effect on either the resistivity or the critical current density of the Bi-2212 phase. Heat treatment conditions and the annealing atmosphere play an important role in determining the critical current density and the transition temperature. Slow cooling from 840°C lowers both the critical current and the transition temperature; while quenching the sample from 840°C to room temperature and annealing it in a nitrogen atmosphere increase both the critical current density and the transition temperature.