Evaluation of in-plane and out-of-plane crystallinities with residual amorphous phases for MgB2 superconductor

We focus on in-plane and out-of-plane crystallinities of the MgB2 superconductor. These two structural properties were evaluated in terms of peak broadening at lower angles in the X-ray diffraction. The angular behavior of the in-plane and out-of-plane peaks was used to compare it with the corresponding behavior estimated in the case of several crystallite sizes (that affect the in-field superconductivity of MgB2). We propose that this comparison allows a simple evaluation to provide insight into the individual influences of in-plane and out-of-plane crystallinities on the in-field critical current density (without needing to calculate numerical values of crystallite sizes and lattice strains of fabricated MgB2 materials). For this study, we used MgB2 samples sintered at different temperatures. The sintering conditions affected not only the crystallinities but also the phase compositions. The behavior of the compositions, including amorphous phases, was also evaluated by using a quantitative analysis for X-ray diffraction results.