Optical Properties of Nanoporous Polycrystalline Anodic Alumina in the IR Region

Abstract

The technology of polycrystalline anodic aluminum oxide (AAO) formation by high-temperature annealing of nanoporous alumina is described. Optical properties in the infrared (IR) spectral range are investigated. It has been revealed that nanoporous ceramics based on polycrystalline AAO has a wider bandwidth and higher transparency than aluminum oxide ceramic corundum (poycor). Analysis of various phases of AAO in the IR range showed that the transparency window widens with the increasing annealing temperature and shifts to the long-wave part of the spectrum: from $5.5\ \boldsymbol{\mu} \mathbf{m}$ for amorphous AAO to $5 \mu \mathrm{m}$ for polycrystalline AAO.