Zirconium aluminides studied with first principles calculations: Hyperfine interactions and site preference of dopants

By means of a density functional theory (DFT) based augmented plane waves plus local orbitals (APW ​+ ​lo) method, we study the electric field gradients (EFG) in Ta and Cd-doped Zr–Al intermetallics. Comparing the obtained results with the experimental data obtained from the perturbed angular correlation (PAC) measurements, we conclude that Ta atoms always replace Zr in all the investigated compounds. Our results confirmed the previous experimental assumption that Cd substitutes exclusively for Al in ZrAl3 and Zr2Al3. In the case of Zr2Al our calculations suggest that Cd can probably substitute on both Zr and Al lattice sites, while in Zr3Al, it is most likely to occupy Al position. The effects of the distance between the impurity atoms in the supercells and the deviation of the c/a ratio are also discussed.