Optical ceramics are typically prepared using micron size starting materials, which requires high processing temperatures and significant grain growth in order to obtain transparency. This results in weaker materials. An alternate is to start with nanomaterials, which can be densified at lower temperatures; however, processing of these materials is more difficult.

Methods were developed to prepare dispersions of nanoparticulates, filtration techniques for preparing green preforms, and methods to transform (by heating) preforms into transparent ceramics. The approaches demonstrated that transparent, strong Yttria (Y₂O₃) parts could be made with a microstructure some 400 times finer than done previously for Yttria IR windows.

Nanomaterials are the fundamental building blocks for many current and emerging nanotechnology applications. The availability of high quality nanomaterials is a critical factor in the eventual development and manufacture of advanced optic, electronic and medical devices.

A Navy SBIR program was used to prepare transparent Yttria with a grain size averaging ~ 0.5 µm and IR transmission of 81% in the 3-5 µm wavelength range. Work focused on consolidation and full densification of parts made from high purity nanoparticles.

The resulting IR transmission curve is shown and it essentially overlaps with a standard material made with 400 µm grains, which is what is available today. Processing methods developed for preparing and handling materials are applicable to other ceramic oxides.

Applications:

Know how for preparing high purity nanomaterials and converting these into transparent parts exists and is available for application where properties such as strength and a tailored index of refraction optics could be valuable.