[en] The hyperfine field at metal lattice sites in a nanostructured HfO₂ thin film was studied by the Perturbed Angular Correlation (PAC) technique using ¹⁸¹Ta as probe nuclei. The thin oxide film was deposited by pulsed laser ablation on a silicon substrate kept at 673 K. The resulting film thickness was about 25 nm. The ¹⁸¹Ta isotopes are formed in Hf sites of the sample as disintegration product of radioactive ¹⁸¹Hf, which were produced by neutron activation of the very thin film by the reaction ¹⁸⁰Hf(n,γ)¹⁸¹Hf. PAC measurements of the electric field gradient at the ¹⁸¹Ta probe sites were performed with the thin film in the temperature range 295 - 1273 K in vacuum. Results showed that the film has a single crystalline structure and two different quadrupole frequencies could be observed corresponding to ¹⁸¹Ta at monoclinic structure and with oxygen vacancy in its neighborhood.