Improvements in the production of Yb:YAG transparent ceramic materials:Spray drying optimization

Spray drying parameters have been optimized for the preparation of granulated stoichiometric mixture of oxides. These oxides are used in the production of Yb:YAG laser grade ceramic materials by reactive sintering. The selected compositions were Yb0.294Y2.706Al5O12 and Yb0.03Y2.97Al5O12, i.e. YAG doped with 9.8 and 1.0 at% of Yb with respect to the overall Y + Yb amount. The influence of solid content, drying medium flux, temperature and aspiration rate of the spray drying process on the transparency of the sintered materials has been evaluated. Sintering was conducted under high vacuum and clean atmosphere in the temperature range of 1650-1735°C and with a soaking time of 16h. SEM analysis of the microstructure of granulated powders and sintered materials, as well as the transmittance measurement, were used as tools to guide the selection of the best spray drying parameters.