| abstract |
The present invention provides a transparent and polycrystalline ceramic having excellent optical quality required for an optical element such as a lens or a prism, and a method for producing the same. Stoichiometry A2 + XBYDZE7, where −1,15 ≦ x ≦ + 1.1 and 0 ≦ Y ≦ 3, and 0 ≦ Z ≦ 1.6, and 3x + 4y + 5z = 8, where A is a group of rare earth ions At least one trivalent cation selected from: B is at least one tetravalent cation; D is at least one pentavalent cation; and E is at least one divalent anion. It is made of transparent, polycrystalline ceramics, and contains at least 95% by weight of crystals having a cubic jadeite or fluorite structure. The average particle size of the optoceramics is preferably in the range of 5 to 300 μm, and the starting material contains at least one sintering aid selected from the group consisting of SiO2, TiO2, ZrO2, HfO2, Al2O3 and fluorides. [Selection] Figure 1 |