Growth of (11n) oriented Bi–Ca–Sr–Cu–O films by liquid phase epitaxial method

Abstract

Films of Bi–Ca–Sr–Cu–O (BCSCO) superconductor of the Bi2CaSr2Cu2Ox composition have been grown by the liquid phase epitaxy method (LPE) using a partially closed growth chamber. The films were grown on (110) NdGaO3 substrates by slow cooling under optimized conditions below the peritectic melting point (885 °C) of Bi2CaSr2Cu2O8. Optimization of parameters, such as seed rotation, soak of initial growth temperature, and growth period, results in the formation of the 2122 phase of BCSCO. X-ray diffraction (XRD) measurements show that the films grown on (110) NdGaO3 have a preferred (11n) orientation. The best values of zero resistance transition (Tc0) and critical current density (Jc0) obtained for films grown on (110) NdGaO3 substrates are 87 K and 5.7 × 104 A/cm2 (at 20 K), respectively. The films grown at rotation rates of less than 30 and more than 80 rpm are observed to be associated with a subphase in the Bi2CaSr2Cu2O8 system. Electron microprobe analysis indicates the composition of this subphase to be Bi0.07Ca0.93Sr2Cu5O8. Higher growth temperatures (>860 °C) also encourage the formation of this phase.