Combining ellipsometric and EIS methods, the dielectric constant ε for the oxide Nb2O5 at room temperature was determined. At first, the linear dependence between anodization voltage and oxide thickness was established in the form d = 2.14 (± 0.05) · U + 12.2 (± 1.7) nm in the range of anodizing potentials 0-50 V. Next, assuming the equivalent circuit corresponds to one, the capacitance C of the dense oxide layer was measured. All results taken together gave the value of dielectric constant ε = 93 ± 5.
Keywords: dielectric constant; electrochemical impedance spectroscopy; ellipsometry; niobium oxide.