Patent ID: 8197711

Claim:
A transparent polycrystalline optoceramic, single grains of which have a symmetric cubic structure, said cubic structure of said single grains being isotypic to that of pyrochlore or fluorite, or unambiguously derivable therefrom in crystal structure terms, with at least one optically active center selected from the group consisting of rare earth ions, transition metal ions and titanium ions, wherein the optoceramic has the following formula: A 2+x B y D z E 7 , wherein 0≦x≦1.1, 0≦y≦3, 0≦z≦1.6, and 3x+4y+5z=8, and wherein A is at least one trivalent rare earth cation and is selected from the group consisting of Y +3 , Gd +3 , Yb +3 , Lu +3 , Sc +3 and mixtures thereof, B is at least one tetravalent cation, D is at least one pentavalent cation, and E is at least one divalent anion, and wherein the optoceramic has a rare earth ion content of more than 100 ppm.