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

The electronic structure of three intermetallic alloys namely Ti3Al, TiAl and TiAl3 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 Am241 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 Ti3Al and TiAl3 the LCAO values show better agreement whereas for TiAl the synthesized LCAO values are closer to the experiment. Effect of titanium 3d 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 Ti3Al, TiAl and TiAl3 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.

Differences in the convoluted theoretical and the experimental Compton profiles of Ti3Al. The PW-GGA (Sup) represents the superposition of theoretical Compton profiles of elemental solids Ti and Al. The PW-GGA is the theoretical calculation of the alloy. Experimental errors (±σ) are also shown at some points.Figure optionsDownload as PowerPoint slideHighlights
► Directional and spherically averaged Compton profiles of Ti3Al, TiAl and TiAl3 intermetallics are reported.
► The profiles calculated from CRYSTAL code are compared with measurements made on polycrystalline samples using 59.54 keV gamma-rays.
► Calculations are overall in agreement with the measurements with some differences in the low momentum region.
► Compton spectra on alloys and elemental solids are used to study charge transfer. applying superposition model.
► Charge transfer from Al to Ti atom is observed in the three alloys which is relatively larger.