The synthesis of yttrium aluminium garnet (YAG or Y₃Al₅O₁₂) has received much attention on account of its use in structural and functional materials. Among its functional properties, YAG possesses a high efficiency of energy transfer and is resistant to radiation damage, which therefore makes it ideal for laser lenses. The usable transmittance range of YAG extends from the UV to the mid-IR range, making it very useful for IR and laser windows, with a very low absorption coefficient . Furthermore YAG displays a cubic crystal structure, which imparts optical isotropy (unlike sapphire). Doping YAG with different trivalent ions changes the optical properties of the doped materials. Whether manufacturing YAG for phosphor applications or ceramic fabrication, fine-sized particles with no agglomeration are desirable.

The paper presents collaborative work between UNIPRESS and The University of Nottingham in the production of transparent ceramic lenses from doped and non doped Zirconia and YAG nanoparticles. Nanoparticles of ZrO2 and YAG have been made using two different hydrothermal techniques. UNIPRESS use a microwave assisted batch reactor and Nottingham has a nozzle reactor which operates continuously. Both systems are currently small scale and can produce materials sub 20 nanometres on g/hr scale.

The paper will describe the various production techniques, the relationship between operating conditions and particle quality, the similarities and differences between the two synthesis techniques, as well as the effect of the raw powders on the quality of the final lens material.