The hyperfine field at 181Ta lattice sites in nanostructured HfO2 thin films
was studied by the Perturbed Angular Correlation (PAC) technique. Thin oxide
films were deposited by Electron Beam Evaporation on a silicon substrate. The
thickness of the films was ā¼100 nm and ā¼250 nm. Radioactive 181Hf nuclei were
produced by neutron activation of the film samples in the Brazilian Research Reactor
(IPEN IEA-R1) by the reaction 180Hf(n,Ī³ )181Hf. PAC measurements were carried
out after annealing at 1473 K. The PAC technique allows the determination of the
electric field gradient (EFG) at the probe sites.