Experimental and theoretical study of the electronic structure of Fe, Co, and Ni aluminides with the B2 structure

The differences in electronic structure of B2-type (CsCl) transition-metal aluminides (FeAl, CoAl, and NiAl) have been investigated hy comparing data obtained using electron energy-loss spectroscopy with theoretical calculations the spectra. The densities of states (DOS) for the three alloys calculated using the ab initio self-consistent linear muffin-tin orbital method within the local density approximation have been compared. Using the unoccupied part of the DOS and the relevant transition matrix elements, energy-loss spectra have been calculated. It is noted that ii rigid band model can only be considered as a first approximation to calculate rile trends iii the electronic structure of the allays. The Al L(2-3) and K edges (providing information on s+d and p symmetry of final states at the Al sites, respectively) and the transition-metal L(2-3) edges (s+d symmetry of final states al the transition-metal sites) have bren studied. Good agreement has been found between experiment and calculations and, from the interpretation of spectral details in terms of site and angular momentum decomposed density uf states, hybridization and interaction between the Al sp and TM d bands is observed and thus a covalent character in the bond is concluded. The differences in the electronic structure of the alloys studied, both iii terms of band filling and density of states at the Fermi level, have been correlated with the variation of the macroscopic properties of the materials.