The influence of the HIP process on the microstructure, critical temperature and critical current density of double-doped (with Dy₂O₃ + C, and Tb₂O₃ + C) MgB₂ bulk compounds

ABSTRACT

We present the results of the irreversibility field (B_irr), critical temperature (T_c), and magnetic critical current density (J_cm) for cylindrical samples encapsulated in carbon and doped with 1-3 at% dysprosium and terbium oxides. All samples were analyzed microstructurally by using a scanning electron microscope (SEM) and X-ray diffraction (XRD). The influence of annealing temperature and time and high isostatic pressure on J_cm was investigated. Our results show that double-doped (C + Tb₂O₃ and C + Dy₂O₃) and low isostatic pressure heat treatment (0.1 MPa) decrease the T_c by about 0.5 K compared to the undoped MgB₂ (0.1 MPa). The magnetic measurements show that double-doped and heat treatment under high isostatic pressure (HIP - 1 GPa) leads to a decrease in T_c of about 2.5 K compared to the undoped MgB₂ sample after the HIP process. Our results show that the HIP process slightly increases J_cm at 4.2 K and 20 K, and improves J_cm at 30 K in undoped MgB₂ samples. Furthermore, our results show that the HIP process and double-doped significantly increase J_cm at 4.2K and decrease J_cm at 30K. Our results indicate that the HIP process can produce high field and low-temperature pinning centers in doubly doped MgB₂ materials.

KEYWORDS:

• High isostatic pressure; MgB2 materials; critical current density

Disclosure statement

No potential conflict of interest was reported by the author(s).