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

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.