Patent ID: 7566408

Claim:
A method of producing polycrystalline yttrium aluminum garnet, comprising: providing a compact comprising at least one powder selected from undoped yttrium aluminum garnet, doped yttrium aluminum garnet, a powder mixture having undoped yttrium aluminum perovskite, and a powder mixture having doped yttrium aluminum perovskite; sintering the compact in flowing oxygen at temperatures of between about 1500° C. to about 1700° C. such that sintered yttrium aluminum garnet is formed; and hot isostatically pressing the sintered yttrium aluminum garnet at temperatures of between about 1400° C. to about 1600° C. for about 5 to about 20 hours and at pressures sufficient to form a transparent polycrystalline yttrium aluminum garnet is formed having a porosity between less than about 3 ppm, and a mean grain size of about 1 to about 2 μm.