First-principles investigation of the superconducting properties of MgXB4 (X = Al, Li, Na, K)

•Based on theoretical and experimental results, four MgB2-like superconductors, MgXB4 (X = Al, Li, Na, K), were designed in this study.•The electronic structure, phonon dispersion relationship, Eliashberg spectral function, electron-phonon coupling constant (λ), and superconductivity of MgXB4 were investigated using a first-principles approach.•The results indicated that MgXB4 (X = Al, Li, Na, K) were dynamically stable and demonstrated metallic characteristics. The calculated superconducting transition temperatures (TC) of MgXB4 (X = Al, Li, Na, K) were 0.12, 22.7, 28.1, and 30.4 K, respectively.