12 - Transparent ceramics based on pyrochlores

Abstract

Transparent polycrystalline ceramics are promising optical materials for laser gain media, solid-state phosphors, scintillators, armor windows, IR domes, and various optical elements. In order to obtain high transparency, high crystallographic symmetries, such as cubic, tetragonal, and hexagonal, are required from a crystal structure point of view. Oxide pyrochlores, a large compound family among ternary metallic oxides with the general formula A2B2O7 (A and B are metals), present cubic structures generally depending on the ionic radius ratios of rA and rB, which make them ideal for transparent ceramics. Moreover, pyrochlores preserve relatively high density and high refractive index, which could lead to potential applications as optical elements and scintillators. This chapter describes transparent ceramic materials based on pyrochlores, including A2B2O7 pyrochlores, A-site and/or B-site substituted A2B2O7 pyrochlores, and new AB2O6 pyrochlores, and their preparation methods and potential applications.