Electronic origin of the stability trend in TiSi2 phases with Al or Mo layers

Through a tight-binding rigid-band approach we show that changes in the relative stability of the C54, C49, and C40 phases of TiSi2, with electrons per atom ratio, are produced by the corresponding differences in the electronic density of states at the Fermi level. In particular, by increasing this ratio the stable phase evolves from C49 to C54, and then to C40. Our microscopic model provides a straightforward interpretation of very recent experimental findings concerning the sizeable variations in the transition temperature between C49 and C54 TiSi2 in the presence of Al or Mo layers. (C) 1998 American Institute of Physics. [S0003-6951(98)03740-1].