Transparent compact ceramics: Inherent physical issues

The overview focuses on inherent optical properties, governed by composition and the state of the crystal lattice, and on the interference of these properties with the microstructural optimization of transparent ceramics (e.g. the dependence of the tolerable pore size or grain size on the refractive index). Starting with the general difference between the dispersive performances n(lambda) of glasses and transparent ceramics, examples will demonstrate the use of compositional changes for tuning the relationship of index, Abbé number, and anomalous dispersion. Perowskites and cubic zirconia are known candidates for such developments, but their mechanical strength is low. Therefore, physical conditions are investigated for bringing translucent tetragonal ZrO2 to transparency. Another field of increasing interest is transparency at extreme wave lengths affected by point defects, associated absorption and scattering mechanisms.