Effect of doping on cohesive and thermophysical properties of MgB2

The effects of doping Al and Mn on the cohesive and thermophysical properties of MgB2 have been investigated using a Rigid Ion Model (RIM). The interatomic potential of this model includes contributions from the long-range Coulomb attraction and the short-range overlap repulsion and the van der Waals attraction. This model has been applied to describe the temperature dependence of the specific heat of MgB2, Mg1−xAlxB2 (x = 0.1–0.9) and Mg1−xMnxB2 (x = 0.01–0.04) in the temperature range 5 K ⩽ T ⩽ 1000 K. The calculated results on cohesive energy (ϕ), Bulk modulus (BT), molecular force constant (f), Restrahalen frequency (ν0), Debye temperature (ΘD) and Gruneisen parameter (γ) are also reported for these materials. Our results on Bulk modulus, Restrahalen frequency and Debye temperature are closer to the available experimental data. The comparison between our calculated and available experimental results on the specific heat at constant volume for MgB2 and Mg1−xAlxB2 (x = 0.1–0.4), particularly, at lower temperatures has shown almost an excellent agreement. The trend of variation of the specific heat with temperature is more or less similar in pure and doped MgB2.