Bi Pb SrCaCuO Thin Films Research Articles

Production of BiPbSrCaCuO Thin Films on MgO and Ag/MgO Substrates by Electron Beam Deposition Techniques

Superconducting BiPbSrCaCuO thin films were prepared on MgO(001) and Ag/MgO substrates using an electron beam (e-beam) evaporation technique. The effects of annealing temperature and Ag diffusion on the crystalline structure and some superconducting properties, respectively, were investigated by X-ray diffraction, atomic force microscopy, and by measurements of the critical temperature and the critical current density. It was shown that an annealing of both types of films at 845 or 860 °C resulted in the formation of mixed Bi-2223 and Bi-2212 phases with a high degree of preferential orientation with the c-axis perpendicular to the substrates. The slight increase of the critical temperature from 103 K to 105 K, the enhancement of the critical current density from 2 x 10 3 to 6 x 10 4 A/cm 2 , and the improved surface smoothness are due to a possible silver doping from the substrate.

Preparation of 110 K BiPbSrCaCuO thin films by d.c. magnetron sputtering and their transport properties

Superconducting BiPbSrCaCuO thin films with a zero resistivity temperature of 110 K and a critical current density of 2733 A cm −2 (at 77.02 K) were deposited on MgO(100) single crystal substrates by d.c. magnetron sputtering. After deposition at 350–400°C and post annealing at 840°C for 1–5 h in air, with different cooling rates, thin films were obtained which were highly c-axis orientated, with zero resistivity temperatures, T c0, of 103–110 K. The thin film samples with a mixture of high (2223) and low (2212) T c phases show a low T c onset and sharp transition in the resistivity-temperature ( R- T) curves with relatively high current densities. The transport properties of the 100 K sample were studied. The temperature dependence of the critical current density exhibits weak-link characteristics. The mechanism of 2223 phase formation is also discussed.