The effect of LiF sintering aid on the degradation of transparent magnesium aluminate spinel during hot‐pressing was studied. LiF is used to etch spinel particles during the hot pressing process. The LiF was found to react with the aluminum in the spinel structure, thereby leaving Mg‐rich regions behind that do not sinter well and result in opaque white regions in the otherwise transparent matrix.

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

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