The Figure provides a comprehensive analysis of the components of the migration barrier Ea(th), namely ΔE and EKRA, and the correlations between ΔE and the ionic radius rB of the transition metal B in MgB2S4 sulfide and MgB2Se4 selenide spinels. It is observed that for larger ionic radii, the site preference energy (ΔE) significantly contributes to the overall migration barrier, while for the smaller ionic radii the contribution of EKRA grows and the site preference energy ΔE diminishes, as shown in Figure . This trend is attributed to trigonal distortion resulting from the size difference between A-metal (e.g. Mg) in tetrahedral 8a sites and B-metal in octahedral 16d sites within the spinel structure. This mismatch causes a noticeable tilt in 16c and 16d octahedrons leading to an increased area in all faces of the tetrahedral site. While all faces of the tetrahedral site increase due to the distortion, only the octahedron faces shared with the tetrahedron are increasing, while others are decreasing in area. As a result, the volume of the tetrahedral 8a sites increases relative to the empty 16c sites, affecting their volume ratio as shown in Figure . Note that if only the B-metal is varied, the trigonal distortion is simply a function of rB, explaining the linear dependence of ΔE on ionic radius (rB) as shown in Figure .