Dielectric study of nanoporous alumina fabricated by two-step anodization technique

Nanoporous anodic alumina (NAA) samples of different porosities were synthesized by electrochemical anodization technique in two different electrolytes (C 2 H 2 O 4 and H 3 PO 4 ) via two-step anodization technique. The dielectric constant and dielectric loss of porous alumina was reported and decreasing trend of dielectric constant and dielectric loss of porous alumina was observed with both applied frequency as well as its porosity. This could be due to the reason that induced dipoles were unable to follow rapid fluctuations of the applied field at higher frequency. The observed dielectric constant of NAA samples prepared in C 2 H 2 O 4 and H 3 PO 4 solutions were 7.84 and 6.27 at 20 Hz, respectively. Owing to porous nature of the material, the resulting samples showed slightly less dielectric constant and exhibited enhanced conductivity as compared to barrier type alumina. Furthermore, a correlation between theoretical results and experimental results were established. Graphic abstract