Enhancement of critical current density for MgB₂ prepared using carbon-encapsulated boron with co-addition of Dy₂O₃ and La₂O₃

In this work, magnesium diboride, MgB₂ samples were prepared by using magnesium, Mg powder and carbon-encapsulated boron, B powder (1.35 wt% carbon) with addition of dysprosium oxide, Dy₂O₃ and lanthanum oxide, La₂O₃ as dopants. Different weight percentages with the ratio of x wt.% Dy₂O₃: x wt.% La₂O₃ were used where x = 0.00, 0.25, 0.50, 0.75, 1.00, respectively. X-ray diffraction (XRD) results confirmed MgB₂ as the major phase for all the samples. Magnetization measurement showed a slight decrease of critical temperature, T_c from 38.1 K to 37.6 K with the co-addition of Dy₂O₃ and La₂O₃. Self-field critical current density, J_c at 20 K increased with the increasing of co-addition levels probably due to improved grain coupling. The highest self-field J_c obtained is 433 kA cm⁻² with 1.00 wt% co-addition level. Field dependent J_c (≤4 T) at 20 K of the co-added samples is higher compared to that of the pure one. The present results show that a small amount of Dy₂O₃ and La₂O₃ co-addition into MgB₂ is effective to enhance flux pinning and J_c.