Modeling the effects of crystallite alignment on birefringent light scattering in transparent polycrystalline aluminum oxide

Transparent alumina ceramics are known for high toughness and the ability to withstand high temperatures, making them ideal materials for use in extreme environments and high-power optical devices. However, polycrystalline alumina, which has a hexagonal crystal structure, is difficult to make highly transparent due to birefringent scattering loss. Research has shown that birefringent scattering can be reduced by having finer grains and/or aligned grains. Here, we present an analytical birefringence scattering model that can model realistic microstructures, by including chord length distributions and grain orientations, and predict the birefringence scattering loss quantitatively. Our modeled results match well with existing experimental data for transparent fine grained and aligned alumina. This model is derived from first-principles and is applicable to other transparent ceramics.