A study of the Fermi surfaces of lithium and disordered lithium-magnesium alloys: theory and experiment

The authors present a theoretical and experimental study of the Fermi surfaces (FSs) of Li and the disordered alloys Li 1-x Mg x (0.6>or=x>0.0) in the BCC phase. Theoretical calculations employ the first-principles fully charge-self-consistent Korringa-Kohn-Rostoker coherent-potential-approximation scheme within the local-density approximation. The experiments involve the two-dimensional angular correlation of positron annihilation radiation measurements on four Li 1-x Mg x single-crystal specimens with x=0.0, 0.28, 0.40 and 0.60. Good overall agreement is found between experiment and theory with regard to the size and shape of the FS as x is increased from 0.0 to 0.6, although some discrepancies are noted. The question of the critical Mg concentration x=x c at which the FS first makes contact with the Brillouin zone boundary in Li 1-x Mg x alloys is considered in some detail.