Magnetic and electrical characterization of Mg1−xKxB2 synthesized from MgB2 and KCl powders

Abstract

This paper reports the effect of doping MgB₂ with K⁺ at different concentrations and sintered at 830°C in its superconducting properties. Samples of Mg_1−xK_xB₂ with 0 ≤ x ≤ 0.5 were prepared and were subjected to SEM, XRD, R-T, I-V and susceptibility measurements. A maximum Tc of 38.4K was achieved at x=0.2 while a decrease in lattice parameter a for doped MgB₂ indicated the successful substitution of K⁺ in Mg sites. K⁺ doping was found to affect the critical temperature of Mg_1−xK_xB₂ in which the hole theory governs before K⁺ saturation and on the other hand the phonon-mediated theory governs after K⁺ saturation. The saturation was found to lie at 0.15 ≤ x ≤ 0.2.