Dielectric properties of laser-ablated HfO$_2$ particles

Dielectric properties of hafnium dioxide (HfO$_2$) nanoparticles obtained by pulsed laser ablation have been studied by impedance spectroscopy in a frequency range from 50 to 10$^5$ Hz. It is established that the dielectric permittivity of obtained particles depends on the degree of porosity of the ablated material, As the porosity decreases, both real $(\varepsilon')$ and imaginary $(\varepsilon'')$ components of the complex dielectric permittivity tend to increase. According to analysis in the framework of the Bruggeman effective medium approximation, the static dielectric permittivity of obtained HfO$_2$ nanoparticles amounts to $\varepsilon'$ = 24 $\pm$ 2.