Compton profile and charge transfer study in intermetallic Ti–Al system

Abstract

The electronic structure of three intermetallic alloys namely Ti 3Al, TiAl and TiAl 3 in terms of Compton profiles is reported in this work. Directional Compton profiles are calculated for all the three alloys employing CRYSTAL code within the framework of density functional theory. The spherically averaged theoretical values are compared with the measurements made using 59.54 keV gamma-rays from Am 241 source. The calculations are in overall agreement with measurements in all cases. The measurements are also compared with the superposition of LCAO profiles of elemental solids. For Ti 3Al and TiAl 3 the LCAO values show better agreement whereas for TiAl the synthesized LCAO values are closer to the experiment. Effect of titanium 3 d electrons is clearly visible in intermediate range of momentum in the Ti rich alloy. Charge transfer in the three alloys has also been estimated following the superposition of experimental profiles of Ti and Al metals. Comparison of Compton spectra of Ti 3Al, TiAl and TiAl 3 with the superposition of the Compton spectra of elemental constituents suggests a charge transfer of 2.8, 0.9 and 0.6 electron per Al atom, respectively. Such large values seem unreasonable and, therefore, this approach cannot be used for any reliable determination of the charge transfer in this system.