Phase separation in garnet solid solutions and its effect on optical properties.

Phase behavior is studied in erbium-doped Y3 Al5 O12 (YAG) garnets synthesized by solid-state reactions. High resolution synchrotron XRD and SEM-EDX studies reveal phase separation at an erbium content between 8 and 50 at%, depending upon the processing conditions. Similar results are found in closely-related garnet systems. The phase separation has a striking effect on the optical properties of YAG:Er(3+) .