Transparent YAG Ceramics for IR Windows Produced from High Purity YAG Nanopowders

Nanocerox proposes to use our custom formulated, high purity yttrium aluminum garnet (YAG) nanopowder for the production of YAG plates (100 mm diameter and 6 mm thick) with 82-84% transmission to demonstrate their utility as IR transparent windows. YAG is a high strength ceramic which, with proper processing, can achieve the optical quality required for this application. The challenge for successful development lies in that very narrow specifications of purity, composition, and processing must be strictly maintained for YAG to achieve transparency. Nanocerox has recently demonstrated its ability to overcome many of these challenges by repeatedly producing YAG ceramics (1~2 mm thick) with 82-84% transmission at 1000-3000 nm. This achievement was made possible by the optimized sintering of high purity nanopowder, prepared by Nanocerox’s patent synthesis method of Liquid-Phase Flame Spray Pyrolysis. The optimized method produces YAG nanopowders with high purity (<200 ppm volatiles, < 50 ppm transition metals), uniform particle size (~ 40 nm average), and strict composition control (± 0.003 variation in stoichiometry). Our Phase I goal will be achieved through a series of specific technical tasks: (1) production of 4 x 2 kg batches of high quality YAG nanopowder; (2) processing trials at an interim size of 40 mm dia. x 6 mm thick to resolve key issues; (3) optical and physical characterization of trials to confirm the performance specifications; and (4) production and characterization of YAG parts in the final target size. Success in Phase I will set the stage for further Phase II development including establishing quality control on large scale nanopowder production; optimized sintering control for maximum physical properties; characterization of physical properties under extreme environments; and fabrication of larger prototypes under consultation with Air Force technical officers.