The current status and advances of polycrystalline YAG in both structural (high temperature) and functional applications are reviewed. A historical background of YAG and its progressive development to its current stage in functional and structural applications is reviewed. This review emphasizes the important aspects of polycrystalline YAG processing-microstructureproperty relationships. For high temperature structural applications, the published mechanical properties (both single and polycrystalline) of YAG are described. Selected structural applications of polycrystalline YAG (e.g., monolith, fiber and CMC matrix) are discussed along with various aspects of processing. For functional applications, the current status of polycrystalline YAG, both doped and undoped, is reviewed from the processing point-of-view. Certain functional applications, including IR/ laser window materials, laser hosting materials, and high intensity discharge lamp materials, are reviewed. Recent research activities carried out in our lab for processing transparent polycrystalline YAG are also described.

Keywords: YAG, high temperature structural material, laser hosting material