Structural variability of gamma Ni-silicides

Studying the Ni-Si system, we confirmed the only known Ni 31 Si 12 ( S12 ) structure and in addition several new gamma modifications were also observed. Our TEM/STEM studies of gamma Ni-silicides revealed crystal structures with different atomic arrangements and even varying c cell parameters (~6 Å, ~12 Å, ~18 Å, ~36 Å). Three of them were determined and named S6a , S6b and S18 . The nomenclature of S6 , S12 and S18 refers to their c cell parameters which are multiples of ~6 Å. Nanoscale variability was also observed in the gamma Ni-silicides, where nanoscale variability was the outcome of stacking, inversion, twinning and intimate (001) intergrowths of the different modifications. • Within the γ-Ni-Si system, several new crystal structures have been observed by TEM. • In addition to the known S12 structure, S6a, S6b and S18 modifications have been identified. • All modifications of γ-Ni-silicides are created by varying the basic units S6a and S6b