The hafnium aluminides HfAl3 and Hf2Al3 studied by perturbed angular correlations with Ta-181 and Cd-111 probes

The electric quadrupole hyperfine interactions for Hf-181/Ta-181 and In-111 /Cd-111 probes in the polycrystalline hafnium aluminides HfAl3 and Hf,AI, w ere measured in the temperature range 30-1100 K. On the basis of the simila rities of the numbers, sizes and asymmetries of electric field gradients, l attice site allocations were made. In all matrices, Hf-181/Ta-181 was found to substitute into the Hf site. The In-111/Cd-111 impurities were also ass igned to the Hf lattice site in the low-temperature phase of HfAl3, which h as DO23 structure, but appear to substitute into the two non-equivalent Al sites in the Hf2Al3 phase, which has Fdd7 crystallographic structure. (C) 2 000 Elsevier Science BN. All rights reserved.