Akademik Veri Yönetim Sistemi
Chinese Journal of Physics, cilt.49, sa.3, ss.809-821, 2011 (SCI-Expanded)
We have investigated the effect of annealing time and temperature on the formation of the MgB2 phase, transition temperature (Tc), lattice parameters (a and c), full width at half maximum (FWHM) of the X-ray diffraction, crystallinity, resistivity (ρ), residual resistivity ratio (RRR), active cross-sectional area fraction (AF), and critical current densities (Jc) of MgB2/Fe monofilament tapes fabricated using an ex-situ powder-in-tube (PIT) method without any intermediate annealing. To obtain the optimum annealing temperature, MgB2/Fe monofilament tapes were annealed at 650, 750, 850, 950, and 1050°C for 60 minutes. From these investigations, the optimum annealing temperature was found to be 950 °C. Then, to obtain the optimum annealing time, the samples were annealed at 950 °C for 15, 30, 60, 120, 180, and 240 minutes. The samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), optical microscope, critical transition temperature (Tc), and critical current density (Jc) measurements. The transport and microstructure investigations show that Tc, Jc, and the microstructure properties are remarkably enhanced with increasing annealing temperature up to 950 °C. The highest value of the critical current density was obtained after annealing at 950 °C for 60 minutes. The Jc and Toffset c values of the sample annealed at 950 °C for 60 minutes were found to be 260.43 A/cm2 at 20 K and 38.1 K, respectively. © 2011 The Physical Society of the Republic of China.