Preparation and Properties of Transparent Scandium Oxide-Modified Nd:YAG Ceramics

— We have studied the effect of Sc 2 O 3 as a modifying additive on the formation of weakly agglomerated single-phase nanopowders of doped yttrium aluminum garnet with the laser composition Y 2.97 Nd 0.03 ScAl 4 O 12 (Nd:YSAG), the fundamental aspects of the preparation of transparent ceramics from the modified powders, and the microstructure and properties of the ceramics. Carbonate precursor powders with a specific surface area of 285 m 2 /g, synthesized via quantitative chemical coprecipitation of metal cations from an aqueous solution of hydrochloric acid salts in the presence of high molecular weight surfactants have been characterized by high-temperature X-ray diffraction. The results demonstrate for the first time that, during the thermal decomposition of the carbonate precursor, the structure of Nd:YSAG is formed in the temperature range 850–1000°C in the form of a metastable nonstoichiometric cubic aluminate, (Y,Nd)Sc x Al 1– x O 3 , with a garnet-like structure. In the range 1100–1150°C, it reacts with the Al 2 O 3 resulting from the decomposition of the precursor to form Nd:YSAG. The synthesized weakly agglomerated spherical nanoparticles and submicron particles with a controlled stable size in the range 100 to 200 nm were vacuum-sintered to give transparent ceramics with an average grain size of 3 μm and high transmission (up to 78%) in the visible spectral region.